GH-133: Fix deprecation warnings

```
/home/kshchepanovskyi/IdeaProjects/protobuf-jetbrains-plugin/src/main/java/io/protostuff/jetbrains/plugin/formatter/ProtoLanguageCodeStyleSettingsProvider.java:47: warning: [deprecation] getDefaultCommonSettings() in LanguageCodeStyleSettingsProvider has been deprecated
    public CommonCodeStyleSettings getDefaultCommonSettings() {
                                   ^
/home/kshchepanovskyi/IdeaProjects/protobuf-jetbrains-plugin/src/main/java/io/protostuff/jetbrains/plugin/formatter/ProtoCodeStyleSettingsProvider.java:34: warning: [deprecation] createSettingsPage(CodeStyleSettings,CodeStyleSettings) in CodeStyleSettingsProvider has been deprecated
    public Configurable createSettingsPage(CodeStyleSettings settings, CodeStyleSettings originalSettings) {
                        ^
2 warnings
```

Author: kshchepanovskyi

src/main/java/io/protostuff/jetbrains/plugin/formatter/ProtoCodeStyleSettingsProvider.java

@@ -3,7 +3,7 @@
 import com.intellij.application.options.CodeStyleAbstractConfigurable;
 import com.intellij.application.options.CodeStyleAbstractPanel;
 import com.intellij.application.options.TabbedLanguageCodeStylePanel;
-import com.intellij.openapi.options.Configurable;
+import com.intellij.psi.codeStyle.CodeStyleConfigurable;
 import com.intellij.psi.codeStyle.CodeStyleSettings;
 import com.intellij.psi.codeStyle.CodeStyleSettingsProvider;
 import com.intellij.psi.codeStyle.CustomCodeStyleSettings;
@@ -31,7 +31,8 @@ public String getConfigurableDisplayName() {
 
     @NotNull
     @Override
-    public Configurable createSettingsPage(CodeStyleSettings settings, CodeStyleSettings originalSettings) {
+    public CodeStyleConfigurable createConfigurable(@NotNull CodeStyleSettings settings,
+            @NotNull CodeStyleSettings originalSettings) {
         return new CodeStyleAbstractConfigurable(settings, originalSettings, "Protobuf") {
             @Override
             protected CodeStyleAbstractPanel createPanel(CodeStyleSettings settings) {

src/main/java/io/protostuff/jetbrains/plugin/formatter/ProtoLanguageCodeStyleSettingsProvider.java

@@ -29,10 +29,7 @@ public Language getLanguage() {
 
     @Override
     public void customizeSettings(@NotNull CodeStyleSettingsCustomizable consumer, @NotNull SettingsType settingsType) {
-        switch (settingsType) {
-            default:
-                break;
-        }
+
     }
 
     @Nullable
@@ -41,19 +38,14 @@ public IndentOptionsEditor getIndentOptionsEditor() {
         return new SmartIndentOptionsEditor();
     }
 
-
-    @Nullable
     @Override
-    public CommonCodeStyleSettings getDefaultCommonSettings() {
-        CommonCodeStyleSettings settings = new CommonCodeStyleSettings(ProtoLanguage.INSTANCE);
-        settings.initIndentOptions();
-        // TODO: we should define our own settings
-        settings.SPACE_AROUND_ASSIGNMENT_OPERATORS = true;
-        settings.SPACE_BEFORE_SEMICOLON = false;
-        settings.BRACE_STYLE = END_OF_LINE;
-        settings.KEEP_BLANK_LINES_IN_CODE = 2;
-        settings.KEEP_LINE_BREAKS = false;
-        return settings;
+    protected void customizeDefaults(@NotNull CommonCodeStyleSettings commonSettings,
+            @NotNull CommonCodeStyleSettings.IndentOptions indentOptions) {
+        commonSettings.SPACE_AROUND_ASSIGNMENT_OPERATORS = true;
+        commonSettings.SPACE_BEFORE_SEMICOLON = false;
+        commonSettings.BRACE_STYLE = END_OF_LINE;
+        commonSettings.KEEP_BLANK_LINES_IN_CODE = 2;
+        commonSettings.KEEP_LINE_BREAKS = false;
     }
 
     @Override