Add some meat to the README.
Some touch-ups to the README.
Perform tag whitelist check on data ingest too

This is because people may submit with an old client that doesn't
whitelist
Send a list containing "unkown" to summary.html if values are unkown

summary.html expects artist, title, release and track number to be
lists. If any of those tags is not a list, it will still access the
first element for printing, which, in the case of unkown values, was
just "[".
Add links back to Musicbrainz Artist, Release and Recording entries
Include microsecond precision in creation of timestamps for stats, to hopefully prevent spikes when multiples get created in the same second due to transactionality.
quote artist/title for Tomahawk embedding
Merge pull request #22 from Freso/readme-update

Add some meat to the README.
Merge pull request #25 from mineo/unkown-fix

Send a list containing "unkown" to summary.html if values are unkown
Merge pull request #26 from JesseWeinstein/add_links

Add links back to Musicbrainz Artist, Release and Recording entries
Merge pull request #28 from JonnyJD/quote

quote artist/title for Tomahawk embedding
Add Twitter timeline to front page.

https://dev.twitter.com/web/embedded-timelines
Changed the language to en
Add emtpy id checking for artist and release
Merge pull request #23 from metabrainz/whitelist-import

Perform tag whitelist check on data ingest too
Merge branch 'whitelist-import'
Merge branch 'master' of github.com:metabrainz/acousticbrainz-server
Use the return value from clean_metadata
Added page titles.
Show metadata for the last 5 submitted tracks