Add draft ChangeLog for 2.2.1 release.
Slightly shuffle some code in __wt_cache_full_check() to minimize the
work.  I don't see a performance improvement, but doing extra work and
reading global transactional information isn't making read-only loads
faster.
minor reformat for markdown (in the documentation)
Fix variable naming: it's called "enabled", not "sync_on_commit".
Merge pull request #1083 from wiredtiger/221-release-changelog

Add draft ChangeLog for 2.2.1 release.
Cut WiredTiger release 2.2.1
Bump release version on develop branch to 2.2.2
Merge branch 'develop' into wtperf-stats