LB-1900: Concurrent request support via child_process exec

If some error in app.js output just set the output to the error body and
error code 400
LB-1900: Concurrent request support via child_process exec

If some error in app.js output just set the output to the error body and
error code 400
LB-1937: Create coveralls.io project for liveblog

Added [Coverage Status] image.
Merge branch 'master' of github.com:nistormihai/plugin-liveblog-embed-server
LB-1937: Create coveralls.io project for liveblog

on the same line.
fix wrong link.
Merge pull request #239 from nistormihai/master

Stable changes.