CartoDB PostgreSQL extension versioning more flexible based on semver
Merge branch 'master' into CDB-3504
Upgrades extension to version 0.4.0
Improve tests for older version strings so we can release cartodb/redis without releasing a new version of the extension that reports the version with the new format
Merge branch 'master' into CDB-3504

Conflicts:
	app/models/user.rb
Reverts extension to version 0.3.6
Compare using semver in load_cartodb_functions
Merge pull request #729 from CartoDB/CDB-3504

CartoDB PostgreSQL extension versioning more flexible based on semver