Slashify .gitignore file.

As for

    https://github.com/github/gitignore/pull/616
[#1] Fix config tests typo.

The underlying failure has already been fixed, but the test name was
still incorrect.
[#5] Extract RedisConn semi-constants to RedisConn.KEYS.

This decreases duplication of Redis key names within the class.
Reduce visibility of RedisConn constants, renaming.

Nothing outside of RedisConn needs to know the precise implementation
of the Redis key names.
Adjust whitespace throughout.
Extract RedisConn payload to private method.
Remove RedisConn#redis,ImapConn#imap accessors.

There is no need for anything outside of these classes to use the
connections directly.
Rename core to base.
Rename read_mailboxes to queue_new_mailboxes_uids.
Merge branch 'refactor' into develop
[#12] Fix Redimap.configure block.

It can be helpful to set a variable as writable, if one wishes to
write to it.
[#2] Implement proper redimap params.

Use `optparse` to process params nicely.
Refactor redimap executable main loop.
[#11] Extend RedisConn#payload to be like Sidekiq.

Add the Sidekiq extra payload information of queue,retry,jid. These are
not used in Resque, but it's nice to have them available for Sidekiq
(and in general).
Bump version to v0.2.0.
Merge branch 'release/v0.2.0'