Fix bug in receiver selection and submission

This closes: https://github.com/globaleaks/GlobaLeaks/issues/255
and: https://github.com/globaleaks/GlobaLeaks/issues/111
Properly visualize also special text fields.
Merge pull request #56 from globaleaks/feature/configurable-settings

updated Receiver,Node and Context to supports advanced conf
Update bootstrap version

Start making home responsive
Set the receivers of the selected context before creating submission

This closes: https://github.com/globaleaks/GlobaLeaks/issues/252
Merge branch 'master' of github.com:globaleaks/GLClient

* 'master' of github.com:globaleaks/GLClient:
  updated Receiver,Node and Context to supports advanced conf
partial supports of advanced settings context+main