Merge remote-tracking branch 'daleharvey/master'
Merge remote-tracking branch 'daleharvey/master'
New test to show bug that occurs when trying to remove a document that was put with a specifiedId.
define module.exports for Node.js
extracting a few useful methods into pouch.utils.js
partial implementation of the pouch adapter API with leveldb as the storage engine

- get, put, attachments, and bulkDocs work (not sure if return values are correct)
- remove doesn't work because of a problem in pouch.utils.js:80 (Pouch is undefined); otherwise should work

TODO: revsDiff, changes, query, replicate, valid, destroy, Changes, *tests*
added levelup as a dependency
implemented api.changes
increment update_seq on each write, save it in by-sequence under 'last_update_seq'
fix a few typos, implement Pouch.valid and Pouch.destroy
some hacks and things to get things in the right place to run tests
comment out idb:// and http:// tests
fix more typos
require() Pouch.merge, set up Pouch as a global var
save and update doc_count in by-sequence store
get attachment tests running, and a few passing even
sort out when to base64 encode/decode attachments
pass tests.bulk_docs.js tests
test.changes.js: all tests passing
conflicts and design_docs tests passing