Clean up spec
Add a helper
Handle messages without a date
Spelling
Version bump for release
Default to baccking up all folders

* Closes #19
Version bump for release
Automatically save on exit if config is modified

* Closes #22
Improve command help
Typo
Whitespace
Order code as per help
Order tests the same as source
Put provider info in a class
Make method private
Simplify class after class extraction

* Now we have Email::provider there's no need to test specific cases.
Invalidate the uid cache when we modify the imap file
Extract an enumerator
Remove unused require
WIP: implement restore