remove typhoeus
add .ruby-gemset and .ruby-version
Don't load tags by id. Load all and mark them as persisted

- Asana::Workspace#tags now perform a single #get(:tags) query instead of reloading tags by Asana::Tag.find, thanks to the ability to mark resource as a persisted one
- Fallback to reloading all tags by get(:tags) and find(id) if necessary
Merge pull request #6 from harleyttd/cache_tags_to_improve_speed

Cache tags to improve speed