Add missing MD5 include.
Fix typos in comments.
Don't include Content-MD5 for form posts, because server doesn't treat the post body normally (servlet API is parsing the body into parameters).
Merge branch 'feature/generic-datum' of github.com:SolarNetwork/solarnetwork-sites into feature/generic-datum

* 'feature/generic-datum' of github.com:SolarNetwork/solarnetwork-sites:
  Fix mapping of percent into array bounds... was not shifting to 0-based length.