Add dynamic version selection

A variable ‘setupBuilderVersion’ will be added to the environment. It can be used to dynamically determine the version used by the build.gradle

Author: gamma

SetupBuilderVersion.gradle

@@ -0,0 +1,17 @@
+
+import org.gradle.util.VersionNumber
+ext.setupBuilderVersion = { 
+
+    def baseVersion = '2.0'                                                 // Base Version to build, depends on gradle version.
+    def version = baseVersion
+
+    // gradle version switch, depends the API level
+    // println 'Gradle version: ' + gradle.gradleVersion
+    def gVersion = VersionNumber.parse( gradle.gradleVersion )
+    if( gVersion >= VersionNumber.parse( '3.0' ) ) version = '3.0'
+    if( gVersion >= VersionNumber.parse( '3.1' ) ) version = '3.1'
+    if( gVersion >= VersionNumber.parse( '3.4' ) ) version = '3.4'
+    if( gVersion >= VersionNumber.parse( '4.2' ) ) version = '4.2'
+    if( gVersion >= VersionNumber.parse( '4.5' ) ) version = '4.5'
+    return version + '.+'
+}

readme.md

@@ -28,6 +28,15 @@ Plugin and Gradle Version
 | 3.4.x          | 3.4 - 4.3      |
 | 4.5.x          | >= 4.5         |
 
+There is a file [SetupBuilderVersion.gradle](SetupBuilderVersion.gradle) to export the required version of SetupBuilder depending on the Gradle version. It can be used to automatically obtain the correct SetupBuilder version.
+
+It can be used as followed:
+
+	apply from: "https://raw.githubusercontent.com/i-net-software/SetupBuilder/master/SetupBuilderVersion.gradle"
+	plugins {
+		id "de.inetsoftware.setupbuilder" version setupBuilderVersion()
+	}
+
 Tasks
 ----
 The plugin add the follow tasks:
@@ -39,9 +48,11 @@ The plugin add the follow tasks:
 Sample Usage
 ----
 ### Base Sample
-    plugins {
-        id "de.inetsoftware.setupbuilder" version "1.8"
-    }
+
+	apply from: "https://raw.githubusercontent.com/i-net-software/SetupBuilder/master/SetupBuilderVersion.gradle"
+	plugins {
+		id "de.inetsoftware.setupbuilder" version setupBuilderVersion()
+	}
 
     setupBuilder {
         vendor = 'i-net software'