Add oFono based cellular network information classes

The classes provide the functionality that the closed source
Harmattan CellularQt.

These classes do not contain any code from CellularQt, only the
interface has been partially replicated based on docs from
http://harmattan-dev.nokia.com/docs/platform-api-reference/xml/daily-docs/libcellular-qt/
Enable oFono-based cellular network time/timezone management

Replace Harmattan CellularQt CSD interface classes with
oFono-based classes that share the CellularQt interface.