95 pg cb v4 4 fix timehandling make installable

Contributes to #95 (closed)

Fix the time-handling. The PostgreSQL CB implementation mistakenly assumed the modification times stored as boost::posix::ptime instances were in GMT but they are actually created as local time values. This caused an extra/redundant conversion to local when storing them. In addition, when retrieving them epoch value from Postgresql it was assumed these values are in GMT, and they are not. The solution:

1. When storing ptime values into postrgresql do NOT convert to local
2. When returning epochs from Postgresql return them as GMT in the result set

Enable installation of Postgresql CB hook library.

This will allow users to configure everything except for client classes.