apt: add big files support

Moved APT-RPM to official CMSSW fork at GitHub and applied all the
current patches.

Implement big files support for 32-bit and 64-bit hosts. Currently
APT-RPM can only handle RPMs, which size is up to 2GB. The new
version can handle big files (64-bit integers are used to store
the size).

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Merge pull request #236 from davidlt/apt-big-files-support

[CMSSW_7_0_X] apt: add big files support