Prepare build environment

1. In case Ubuntu 14.04:
- add devops repository and install multistrap version 2.1.6
- Pin multistrap version 2.1.6
2. In case Ubuntu 12.04:
- add chris-lea (for nodejs) repository with higher priority
- install nodejs from chris-lea repository
3. For all distributions
- fixed npm global installation permission issue
- ensure bc package is present for make img target

Closes-Bug: #1337343
Closes-Bug: #1312654
Change-Id: I62ba9257fb3d575d996bf4c57b5d983c0050fd3b
Merge "Prepare build environment"