If node is not installed and we are not ubuntu precise tell the use to do it manually

Fixes: https://github.com/globaleaks/GlobaLeaks/issues/393
Merge branch 'master' of github.com:globaleaks/GlobaLeaks

* 'master' of github.com:globaleaks/GlobaLeaks:
  fix against issue: https://github.com/globaleaks/GlobaLeaks/issues/449
  fixed issue https://github.com/globaleaks/GlobaLeaks/issues/424
  path bugfixinng in sign-release script
  updated build-glclient to take care of local GLClient build revisions.
  .travis.yml aligned to GLClient and GLBackend
  minor correction against commit https://github.com/globaleaks/GlobaLeaks/commit/c41dfa4761f82239ced0864159d32770eea7fc98
  fixed a bug in build scripts related to AUTOYES option
  added AUTOYES for travis build script
  minor corrections to build scripts