APY-120 : Add support for mongoengine

Added the mongoengine support, currently is should provide
basic support.
APY-120 : Add support for mongoengine

Added validations based on mongo engine meta mapping.
APY-121 : Polymorphic support for models

Done the polymorphic encoder and query merging,
still required the decoder.
APY-35: Implement PO files management
added more configs, better naming of classes, better error handling, cleaning useless code

APY-47: Refactor CDM to include content metadata and make it extensible
updated metadata handling, remove path now removes metadata, updated API for CDM
fixed imports
applied modifications from review
added updateMetadata when fileObj is used
refactor po file manager
Merge pull request #111 from mihaigociu/apy-8-implement-x-filter

APY-16 Implement version support in CDM; Tool for generating a doc file that contains mapping of Method-URI-Service call
Updated Babel library to version 1.3
Updated gitignore
Clean up unneeded files
Tool for generating a doc file that contains mapping of Method-URI-Service call
Work on APY-16 Implement version support in CDM
Updated config file paths for superdesk
SQL Alchemy issue
Update cdm plugin to work with versioning: APY-16
Removed unnecessary imports
Updated gitignore
APY-35: Implement PO files management - merge

Conflicts:
	components/ally/__unit_test__/ally/cdm/impl/local_filesystem.py
	components/ally/ally/cdm/impl/local_filesystem.py