:lipstick: make semi-colons consistent
Make loading date value formatted consistent with user preference

I noticed in one of your gifs that the date format string wasn't being applied
to the fake date used while blame is loading.

Test Plan:
Changed my date format string, then opened blame on a big file with a
complicated history.
Merge pull request #30 from dmnd/linting

Fix some lint that's been bugging me
Merge pull request #32 from dmnd/loading-polish

Make loading date value formatted consistent with user preference
Merge branch 'master' into update-upon-save
Actually update blame view upon save

In the last commit I think I simplified the code and tricked myself into
thinking I tested it, but I must have not reloaded the package. This commit
works though.

Test plan:

First test editing when view is open:

 * Open blame
 * Add some newlines
 * Save file
 * See blame view update

Now test it updates upon second display:

 * Open blame
 * Close blame
 * Add some newlines
 * Save file
 * Open blame again
 * See it update
Fix default date format string at startup

Not sure what happened when I tried to do this in 39133b1, but evaluating
`DEFAULT_DATE` at import time doesn't work because `atom.config.get` returns
undefined. So calculate it later and cache it.

Test Plan:
Reloaded window then opened blame in a big file. Saw my preferred datestring
and not the full ISO 8601 format.