(#445) - Implement Incremental MD5 calculation

Replace jkmyers-md5 with Spark-MD5 in order to calculate MD5 hashes
incrementally. The use-case for this change is to avoid blocking the UI
thread when adding large attachments.
(#2500) - Remove shorter timeout and enable saucelabs
(#2468) - Document PouchDB Collate as external resource
(#2473) - Make changes batch size configurable
(#2457) - don't set error.message
(#1932) - Implementing blog pagination
(#2403) - fix up sync/replication docs
(#2511) - add Pouch Mirror and Filter Pouch to external.md

Another day, another PouchDB plugin. :)
(#1993) - Added version to download button
(#2509) - fix unintentional italics
(#2466 #2475) - replicate using changes with include_docs

Also, to fix #2475 we use open_revs="all"
so that the URL is not too long.