remove eclipse specific files and modify .gitignore (fixes #4)

also:
* merge .gitignore and yo/.gitignore (good practice to have only one gitignore per project)
* add camunda nexus repository until webapp-alpha5 is on central (see issue #9)
Merge pull request #10 from holisticon/4_gitignore

remove eclipse specific files and modify .gitignore (fixes #4)