Use pkg_resources.Requirement for Python versions

This makes possible to specify version diapasons in YAMLs
like "0.6,<0.8" instead of hardcoding something like 0.6.1.

Implements: blueprint pip-style-versions

Change-Id: I515cdc739b110502cf70fb77166ffee8c6a19c24
Look for requested pypi package version

Old implementation requested only the latest version
for required package, e.g., making impossible installing
kombu==1.0.4 while the latest was 2.5.10.

New implementation loads all available versions and chooses
the latest one that meets existing requirements.

Change-Id: I6618707b58419c6e8274742c6a3ddabff6b4cdd9
Use nodejs from EPEL

Additional profit: one cannot run yum install $local_file
successfully if the package is installed, so, if you install
nodejs from a local file, you cannot run installation process
twice.

Change-Id: I62f2f27c9b3835879f0cde07fcd27720e3ef2f31
Add restart action

Change-Id: I8192193c01ef2617c88b688c6614db0ea35f439c