Partial and machineless

Changes include:
* `PostgresInterface` interface changed :),
* server now understands partial transactions and bills,
* in case of machine going offline server automatically sends tx after `SESSION_TIMEOUT `.


Nope, it's [this](http://en.wiktionary.org/wiki/vel), it's usualy used as `or, more properly, ...`

I thought it was common, but if not I will change it to just `or`.