Add locale support on custom import view*

Should update it on the project page in Example9 on http://fivell.github.io/active_admin_import/

```
<p>
  <%= raw(@active_admin_import_model.hint) %>
</p>
<%= semantic_form_for @active_admin_import_model, url: {action: :do_import}, html: {multipart: true} do |f| %>
  <%= f.inputs do %>
    <%= f.input :file, as: :file, label: t('active_admin_import.file') %>
  <% end %>
  <%= f.inputs t("active_admin_import.csv_options"), for: [:csv_options, OpenStruct.new(@active_admin_import_model.csv_options)] do |csv| %>
    <% csv.with_options input_html: {style: 'width:40px;'} do |opts| %>
      <%= opts.input :col_sep, label: t("active_admin_import.col_sep") %>
      <%= opts.input :row_sep, label: t("active_admin_import.row_sep") %>
      <%= opts.input :quote_char, label: t("active_admin_import.quote_char") %>
    <% end %>
  <% end %>

  <%= f.actions do %>
    <%= f.action :submit, label: t("active_admin_import.import_btn"), button_html: {disable_with: t("active_admin_import.import_btn_disabled")} %>
  <% end %>
<% end %>
```

Conflicts:
	config/locales/en.yml

Author: ifyouseewendy

config/locales/en.yml

@@ -2,6 +2,7 @@ en:
   active_admin:
     import: "Import"
   active_admin_import:
+    file: 'File'
     file_error: "Error: %{message}"
     file_format_error: "You can import only valid csv file"
     file_empty_error: "You can't import empty file"
@@ -15,4 +16,8 @@ en:
       other: "Failed to import %{count} %{plural_model}"
     import_model: "Import %{plural_model}"
     import_btn: "Import"
-    import_btn_disabled: "Wait..."
+    import_btn_disabled: "Wait..."
+    csv_options: "CSV options"
+    col_sep: 'Col sep'
+    row_sep: 'Row sep'
+    quote_char: 'Quote char'

config/locales/zh-CN.yml

@@ -3,6 +3,7 @@ zh-CN:
     import: "导入"
     do_import: "导入"
   active_admin_import:
+    file: '文件'
     file_error: "导入错误: %{message}"
     file_format_error: "请您上传 CSV 格式的文件"
     file_empty_error: "您上传的文件为空"
@@ -17,3 +18,7 @@ zh-CN:
     import_model: "导入%{plural_model}"
     import_btn: "导入"
     import_btn_disabled: "请稍等..."
+    csv_options: "选项"
+    col_sep: '列分隔符'
+    row_sep: '行分隔符'
+    quote_char: '引用字符'