open web apps

I renamed my app from 'Unhosted apps' to 'Open web apps' because it's clearer.

This app is aimed at advanced users who want to experiment with new web technology such as Mozilla's Open Web App manifest format and connecting unhosted web apps to your ownCloud data via the remotestorage protocol. this pull request is the cleaned-up version of https://github.com/owncloud/apps/pull/47