* moved wallet, server, lib into electrumx main module
* fixed imports and other path references affected by electrumx main package
* fixing formatting to pass the pycodetest on travis
- the object also manages unflushed history
- the history DB has its own version, starting at 0
This is the first step to making history management into
a separate service and to larger block sizes.
The next step is an improved history format, which I hope will both
save space and be a solution to issue #185. The DB should be able to
upgrade in-place without re-syncing the chain.
