Add Frontier support for Python (DBAPI) and SQLAlchemy

There are 2 main commits:

  * The first adds a Python DBAPI module for the frontier_client library (based on a ctypes binding).
  * The second one makes SQLAlchemy aware of Frontier via the Python DBAPI as an Oracle subdialect.

This is required for the new scripts for the new design of the Conditions DB.

I checked the commits by building/installing with PKGTOOLS/cmsBuild and then in one of the latest 70X IBs I copied the new toolfiles into the available/ folder, then run scram setup and cmsenv and tested that I can use SQLAlchemy and the frontier modules.

Sending now to be discussed in tomorrow's DORP.