Removed hard dep. on PHPCR-ODM

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | technically
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #121 
| License       | MIT
| Doc PR        |
hmm .. I would use ``1.2.0@dev`` here