Stub more specs, refactor mock views

Because .yajl templates are evaluated as Ruby code, it's possible to
load one from within another; this allows us to avoid duplication of
entity data in any of the pluralized methods like `get_projects`,
`get_suites`, and `get_runs`. The definitive JSON data for these will
instead be stored in the corresponding single-entity mock directories,
uniquely identified by their numeric ID.
Fill in Run specs (full coverage)
Improve exceptions