add bitcoin receiving address to profile
log changes to participants table
add db rule to log changes to bitcoin_address
test bitcoin.json, validate bitcoin address, and move migration to branch.sql
refactor bitcoin form to make it inline on profile page
fix javascript issue that triggers edit form on a click event (bitcoin address)
fixes https://github.com/gittip/www.gittip.com/pull/1437#issuecomment-24786372
Merging with master PR #1437 for fixing #1163
This introduces bitcoin address field in gittip profile