praw 7 work -- Test

Add test for sending message from sr. Remove unnecessary blank line in
CHANGES.rst, matched naming conventions within init
praw 7 work -- from_sr test case

Wrote test case for sending message from a subreddit. Messages from
subreddits have no author and instead have a subreddit attribute
praw 7 work -- test accuracy

Changed send_from_sr test so that it ensures the message has come from
the correct subreddit, rather than any subreddit.
praw 7 work -- test rearrangement

rearranged the send from sr test so it is in alphabetical order with the
other tests. Preparing for push to master
Merge pull request #1 from voussoir/praw-work

Praw work self-pull