fixed gazebo_plugin
added missing materials
added gitignore
avoid error message
Merge pull request #50 from ipa-fxm/groovy_dev

Some fixes
Merge branch 'groovy_dev' of github.com:ipa320/cob_environments into groovy_dev
Merge pull request #53 from ipa-nhg/groovy_dev

define default robot_env parameter
Merge branch 'groovy_dev' of github.com:ipa320/cob_environments into groovy_dev