(#1797) - fix websql compaction

Somehow #1743 introduced a regression to WebSQL
where the "compact a complicated tree" test fails.
The fix is to rephrase the query to avoid param
lists (`WHERE foo in (?,?,?)`).

Reproduced in both Safari 7 and Chrome.
(#1795) - better contrast for code colors
(#1807) - import promises once in utils
(#1810) - Remove bower
(#1780) - add bootstrap-style alerts to blogpost
(#1814) - Add notice about database migration to release notes
(#1817) - Change navigation text to API
(#1819) - Fixed documentation typo
(#1658) - integrate persistent mapreduce

This commit ensures that the persisted map/reduce
indexes are destroyed when their parent database
is destroyed.
(#1818) - Tidy alerts
up version to 2.2.0-alpha
(#113) - Initial infrastructure for performance testing
(#1834) - More performance tests

Also updated CONTRIBUTING.md to explain how
to access performance tests.
(#1821) - Fix hotlink
(#1765) - Make npm run build-site rebuild css on less changes
(#113) - Ensure perf tests get build on first run (and tweak docs)
(#1752) - Scrollspy on side nav on api page