pull tweetlimit from env vars

and set default to once per hour
add a quick readme
disqualify tweets with links
use tweet entities instead of text extraction

allows us to remove twitter-text-js module, which is cool but unneeded
since twitter does it for us on the server side and sends us phat json
clean up a bit

add repository since npm warns otherwise
dont bother to write to file anymore
refactor style to be slightly more clever and terse