Work on unit tests for multiple backends

- Unit tests now use the NUnit parameterized test suite feature
  to run multiple times on different backend versions
- Each parameterized run consults a version-specific env var
  for the conn string (e.g. NPGSQL_TEST_DB_9.1)
- If the version-specific env vars aren't defined, a compiled-in
  default connection string is used instead (simply run against
  localhost:5432). This would be the normal mode for developers.
- As discussed on the devel list, removed testing for protocol 2
Merge pull request #108 from roji/parameterized_tests

Work on unit tests for multiple backends
Build to bin instead of src/bin
.gitattributes has packages/* set to binary

To avoid git doing CRLF->LF in packages
Also killed old .cvsignore
Added project nuspec
Merge pull request #109 from roji/nuget

Add nuget spec file + minor stuff
Fixes to .gitattributes and .gitignore
Bumped version to 2.1.0
Changes to project README and related

* Updated license to 2013
* Updated README.txt to point to github
* Removed ChangeLog and RELEASENOTES
replace BufferedWriteStream by BufferedNetworkStream
Merge branch 'master' of https://github.com/npgsql/Npgsql.git into multiple_notify_fix
add constructor for NotifyTest