remove `return`s and clean up some conditionals
Refactor last year chart

Pulled some instance variable assignment into the controller.

Also extracted a method regarding interpolated values for the present
month.
Merge pull request #190 from crymer11/master

remove `return`s and clean up some conditionals
Extract behavior from Todo.from_rich_message

`Todo.from_rich_message` was partially tested from the MessageGateway,
but it is mostly untested and does not belong in Todo due to it's unique
nature. Extract it entirely from `Todo` into it's own dedicated object
for unit testing.
use a null object like a boss
TodoFromRichMessage is really a service object
fixed next month label for calendar view
Pull out RichMessageExtractor

No need to have it embedded
  when it should be unit tested!
Shifting more instance variables to the controller

Also removing some instance variables that were never invoked in the
views. This sets up a future refactoring of the method of comptuting
rolling averages, which differs between the two types of "last year"
views being refactored.
Merge pull request #191 from doncruse/master

Refactor last year chart
Merge pull request #192 from crymer11/master

use a null object like a boss
Merge pull request #194 from stacyvlasits/master

fixed next month label for calendar view
Merge pull request #193 from mattdbridges/extract-rich-message

Extract behavior from Todo.from_rich_message