[zen-60] Make doctrine/common an optional dependency
[zen-60] Make doctrine/common an optional dependency

- Marked doctrine/common via require-dev and suggests in composer.json
- Updated travis config to pass --dev flag to composer
- Added test constant flags to test configuration to skip annotation
  tests unless flag is true

akrabat/zend-form,adamlundrigan/zend-form,akrabat/zend-form,MadCat34/zend-form,marek-saji/zend-form,marek-saji/zend-form,svycka/zend-form,svycka/zend-form,MadCat34/zend-form,adamlundrigan/zend-form,zendframework/zend-form,zendframework/zend-form