Merge pull request #134 from dacrome/BT-36

[fix] bug BT-36 to support not operator with extension fields
[enhancement] bumped version of hibernate, spring and guava
Merge pull request #136 from dacrome/bumped_library_versions

[enhancement] bumped version of hibernate, spring and guava
Merge pull request #135 from dacrome/BT-36

[cleanup] add on constraint to the extension join to create correct
[enhancement] add index and batchsize annotations
[enhancement] add entity graph and change index annotations
[task] removed entity graph because eager fetching increase fetch time
[fix] OneToOne because meta should only reference to one resource entity
[refactoring] removed null check on extensionFieldValues

extensionFieldValues is always initialized.
rename getter and setter of extensionFieldValues.
Null check in ExtensionConverter's toScim and fromScim.
[fix] removed unique constraint

until we know how jpa merge changes and in which order
[task] reset to upstream develop
Merge pull request #138 from dacrome/performance

[task] performance
Merge pull request #137 from davidmoebius/cleanup

[cleanup] and adding license header
[task] move extension update code in distinct ExtensionUpdater class
[task] extended ExtensionUpdater to support delete
[fix] change from MultiValueAttribute to Email type
[fix] now getting right exception if filter field not available
[task] refactor update Extension and adding some unit tests
[refator] deletion of activation token changed to scim standard
[cleanup] removed unused method