added model association tests for activity, belongs to user and has many adventures
added has many through associations for activity model
ran rspec install command, generated .rspec and spec helper
added association specs for adventure model
added association specs for story model
added association specs for user model, edited user, story, and adventure models and specs
edited activity model and activity spec
refactored models with aliases
removed story model
Merge pull request #2 from higginsmt/model-association-tests

Model association tests