Fix type id

This commit improves the structure of the type id as it may be used by
third party clients. The id now defines the build system and the nature
of the project.

Because STS hardcodes those IDs, a new (deprecated) property on type
has been introduced to keep track of them. When serving the legacy HTML
page that STS parses, those ids are used instead.

Fixes gh-39

initializr-service/application.yml

@@ -117,19 +117,23 @@ initializr:
           description: Support for CRaSH
   types:
     - name: Maven POM
-      id: pom.xml
+      id: maven-build
+      sts-id: pom.xml
       default: false
       action: /pom.xml
     - name: Maven Project
-      id: starter.zip
+      id: maven-project
+      sts-id: starter.zip
       default: true
       action: /starter.zip
     - name: Gradle Config
-      id: build.gradle
+      id: gradle-build
+      sts-id: build.gradle
       default: false
       action: /build.gradle
     - name: Gradle Project
-      id: gradle.zip
+      id: gradle-project
+      sts-id: gradle.zip
       default: false
       action: /starter.zip
   packagings: