Update packages

Pinned to log4net 1.2.11 to be compatible with Azavea.PDF and to avoid
1.2.12 which includes a templated assembly info directive that is a
duplicate of one that we have already added to all of our assemblies.
Add pack and push scripts

For easy package distribution
1.2.0
Merge pull request #3 from jwalgran/nuget

Update packages