(#635) - compact deleted document (test)

Added test so we make sure that also deleted document get compacted
(#635) - compact deleted document as well

Now deleted document are also compacted.
(#635) - low level method document availability support

parseDoc and merge have to support new availability option
(#635) - api.get support availability in rev tree
(#635) - make comapction use status from rev_tree

Start with idb adapter
(#635) - refactor websql and leveldb adapters