Revert "SONARJAVA-438 Remove JavaSourceImporter"

This allows to execute integration tests with SQ lower than 4.2.

This reverts commit 82c102eb42b7a4045647b9d1a2605ec0d6e2dd9a.

Conflicts:
	sonar-squid-java-plugin/src/test/java/org/sonar/plugins/java/JavaSquidPluginTest.java