[cleanup] Added access to EntityManager throug the FilterParser Interface
[cleanup] Removed tests for setters and getters
[enhancement] added getFieldForName() method
[enhancement] Enable filtering of extensions
[enhancement] switched from recursive filter parser to an iterative one
[enhancement]  filtering of extensions
Merge remote-tracking branch 'wallner/filter_extensions' into iterative_filter_parser

Conflicts:
	resource-server/src/main/java/org/osiam/storage/filter/FilterConstraint.java
	resource-server/src/main/java/org/osiam/storage/filter/FilterParser.java
	resource-server/src/main/java/org/osiam/storage/filter/GroupCombinedFilterChain.java
	resource-server/src/main/java/org/osiam/storage/filter/GroupFilterParser.java
	resource-server/src/main/java/org/osiam/storage/filter/GroupSimpleFilterChain.java
	resource-server/src/main/java/org/osiam/storage/filter/UserCombinedFilterChain.java
	resource-server/src/main/java/org/osiam/storage/filter/UserFilterParser.java
	resource-server/src/main/java/org/osiam/storage/filter/UserSimpleFilterChain.java
	resource-server/src/test/groovy/org/osiam/resources/helper/FilteredSearchSpec.groovy
[fix] passing through criteria builder instead of entity manager
[cleanup] organizing imports and formatting
Merge pull request #71 from tkrille/merging_iterative_filter_parser_and_extension_filter

Merging iterative filter parser and extension filter