Build and package che-theia plugins during che-theia image build.

[sunix]

The same way we are building extensions, we would build che-theia plugins from sources and package them so they are available right away.

1. skate board step: Build che-theia plugins from che-theia-dev builder container rather than getting it from released travis built #43
2. moto cycle step: include che-theia plugins build into the che:theia generator
   • che:theia init would also clone plugins projects

     ${theia}/che/<clone ext/plugins repos>
     ${theia}/packages/<ln -s extensions>
     ${theia}/plugins/<ln -s plugins>
     

• it would use a single extensions.yml file. we would specify which project is plugin:
  - move extensions/extensions.yml to che-theia-init-sources.yml
  - renamed folders to extensions , root extensions to sources and adding new folders for plugins: plugins
• build all the plugins ${theia}/plugins with a single command: provides a script located in plugins folder that would perform yarn on each plugins.
• packaging the future content of /default-theia-plugins/: the script foreach_yarn is also copying the .theia files in production/plugins folder.
• update CI Using latest che theia generator. Introducing che-theia-init-sources.… #201

[benoitf]

I like the proposal

probably rename extensions.yml to a more generic name (as for now extensions.yml was only for extensions)

I think we can avoid default (no need of compatibility AFAIK)

[AndrienkoAleksandr]

+1 For generic name.

[sunix]

• che-theia-customizations.yml ?
• customizations.yml ?