[FEATURE] Add deleteDatabaseIfExists() method to helper

Similar to createDatabaseIfNotExists() this can be sued to delete a
database if it exists.
[TASK] Merge Doctrine ODM based implementation

This change merges the Doctrine ODM based implementation from the
doctrine branch into the master branch.
[MERGE] Merge Doctrine branch into master
[TASK] Update composer dependencies
Merge remote-tracking branch 'origin/1.0'
[TASK] Mark it as the fork
[TASK] Fix composer.json to match the right repository
[BUGFIX] composer.json
[TASK] Set fixed dependency on doctrine/couchdb-odm on alpha2

Package is not compatible with alpha3
or current master of couchdb-odm
Merge pull request #1 from beechit/master

merge of the branches