released archetype-plugins for slim3-1.0.16, appengine-1.7.5
Added appengine-maven-plugin and changed project structure.
Added .gitignore to eclipse generated files.
Merge pull request #1 from vvakame/archetype-update

Updated archetype-plugins for slim3-1.0.16, appengine-1.7.5
Merge pull request #2 from vvakame/add-appengine-maven-plugin

Added appengine-maven-plugin and changed project structure.
Merge pull request #3 from vvakame/add-gitignore

Added .gitignore to eclipse generated files.