Resolver bundles support

A resolver bundle is a directory, which may or may not be compressed into an archive, that contains all the files that belong to a resolver plus metadata.

This pull request adds support for installing (and removing) resolver bundles, both compressed and uncompressed. It also allows Tomahawk to display some metadata about a non-Attica resolver, and load additional scripts before the main script.

Please take special care when reviewing commit 4d2a942, I'm not very happy about how it passes around the additional script paths but haven't found a better solution.

See the related pull request in tomahawk-player/tomahawk-resolvers.