Switch application timezone to UTC

[dhedlund]

The application's default timezone is currently "Pacific Time (US & Canada)" (defined in config/application.rb. We can to change this to be UTC since our app is now has full multi-tenancy timezone support.

The application's timezone should be set to UTC so that all times gets stored in the database in UTC/GMT time (assuming this isn't already the case with both PostgreSQL and SQLite). A migration script may be necessary to shift times already in the database so they are also in UTC.

Some specs, especially older importer-related ones, make assumptions that their fixtures/samples will always be parsed in Pacific Time and mix tests that have timezones embedded in the date strings they parse with tests that don't.

[lindsaycaron]

I think is correct and can be closed now. Daniel, let me know if you agree! Thx!