Add Support for PRAW 5.0.1

[toddrob99]

This pull request includes updates to all files to reflect changes in PRAW 5.0.1.

• Add USER_AGENT variable to README.md and sample_settings.json, to allow individual bot runners to add their subreddit and/or user id
• Update praw initialization format
• Replace r.get_subreddit with r.subreddit
• Replace subreddit.get_new() with subreddit.new()
• Replace r.submit() with subreddit.submit() and adjust params
• Replace sub.sticky() with sub.mod.sticky() and sub.unsticky() with sub.mod.sticky(state=False)
• Replace sub.set_suggested_sort() with sub.mod.suggested_sort()
• Update OAUTH setup instructions in README.md
• Update setup.py to remove call to deprecated r.set_oauth_app_info, replace r.get_authorize_url with r.auth.url, and remove reference to uniqueKey
• Add identity scope to setup.py, so in the future we can print the username associated with the refresh token if needed
• Change redirect_uri to http://localhost:8080 as suggested in the praw documentation -- although the URL doesn't really matter since we only need to copy the code from the address bar

[toddrob99]

Note: #32 includes praw 3 syntax that #35 does not account for. The suggested sort syntax will need to be updated in whichever branch is merged second (sub.set_suggested_sort() -> sub.mod.suggested_sort()).

[toddrob99]

BTW, as of tonight (8/12/2017), u/PhilsBot is running in r/Phillies with these changes on PRAW 5.0.1.