Stable build

[daniviga]

Closes #43 and closes #63

This is the last step to have a fully automatic delivery of stable installer. Jenkins has been updated accordingly.

https://ci.openquake.org/job/builders/job/installers-builder/48/

• openquake-py27-macos-2.7.0-1.run
• openquake-py27-linux64-2.7.0-1.run
• OpenQuake_Engine_2.7.0-1.exe

[micheles]

LGTM