refactor LHLogger

[ronnno]

LHLogger was implemented before scribe was extracted as a standalone message.
Most of the functionality it introduces already exists in scribe (contextual tags). It adds two things that scribe does not provide today:

1. Dynamic field values - currently log.Stringable() does not indicate if String() is executed during WithTags and the result cached, or later, on each invocation of Info/Error.
2. Debug level

The proposed refactor includes removing LHLogger and replacing it with direct use of scribe:

1. TBD - add &1 and/or &2 to scribe after discussion (@electricmonk ?) and remove or shrink scope of LHLogger
2. Stop storing logger object in long lasting structs - because it ignores the contextual nature of scribe logger objects
3. Create a local logger object in each long lasting go-routine. enrich it with node address etc.
4. in each select case clause set proper entry point and contextual data for the current request
5. attach logger to func calls as parameters instead of relying of access to long lasting structs to promote contextual logging