Use 'is' rather than '=='
tests: Use the real EL 5 tags
Remove some unused imports
models: Add a new ReleaseState enum
releases: Use the new ReleaseState enum

The locked attribute has been misleading for years: we stopped locking
releases and instead were using it for 'pending' releases.

We're going to need more release states though.
enums: Override the create and drop methods

Without this, we won't be able to create or delete enum types in
alembic migrations.
releases: Migrate the DB to the new release states
Only get candidates in active releases
Rename validate_tags to validate_build_tags

I'm about to introduce a new validator which validates tags themselves,
i.e whether they exist in the build system.

Given that the current validate_tags is instead used to validate that a
build has proper tags, it seems appropriate to rename it.
buildsys: Add a getTag method

Koji provides this method to get the information about a tag.
schemas: New schema to save releases
validators: Allow validating Koji tags
validators: Validate the new ReleaseState enum
releases: Implement creation/edition of releases

Releases can never be deleted, they should be archived.
tests: Check creation and edition of releases
Rename the createrelease tool

It is about to be able to do much more than that...
managereleases: Create releases

This uses the web API instead of accessing the DB directly, which will
allow releng to run the command from any machine.
managereleases: Get details about a release
managereleases: Edit a release
Merge pull request #61 from bochecha/releases

Release management