Travis: branch spec switch from white- to blacklist

Instead of only building master and master-1.2.x, we now build all
branches except master-2.0.x.

This allows users who fork the main repo and create feature branches
have them go through the build process
(issue #10873) Fixes missing version on roadmap

Bugs with a target version that is inherited from a parent project
are not shown on the roadmap.
This fixes this and leaves the caching feature intact.
Whitespace, remove commented code and unnecessary cast
Fix #10873: version inheritance in roadmap and changelog

Many thanks to Peter Bruin for providing a fix for this long-standing
issue.
Backport travis_before_script.sh from master branch

- remove crypto_master_salt
- inherit_global is int, not bool