Fixes config-issue
Adds PHP5.5 to travis-build
Skips form-validation test due to ZF2-Issue

Due to an error in the handling of required but non-existent form-fields
in Zend\InputFilter\BaseInputFilter since zf2.1.5 (which has been closed
but reopened a few days later due to a erroneous filter in the
file-uploader).
Merge pull request #2 from heiglandreas/hotfix/configIssue

Fixes config-issue