Adding "sudo: false" to allow faster builds on Travis.

See
http://blog.travis-ci.com/2014-12-17-faster-builds-with-container-based-infrastructure/
for more info.
Removing out-of-date __version__ in sub-packages.
Merge pull request #435 from dhermes/remove-old-versions

Removing out-of-date __version__ in sub-packages.
Merge pull request #433 from dhermes/enable-docker-on-travis

Adding "sudo: false" to allow faster builds on Travis.
Fixing README.rst to render correctly on PyPI.

Main changes:
- Using named links instead of anonymous
- Using an absolute instead of project relative link for
  CONTRIBUTING
- Changing duplicated link text so that they differ
- Lining up :target: with the line above for embedded img's

H/T to
https://github.com/coagulant/coveralls-python/blob/master/README.rst
for guidance.
Fixing final relative link and de-denting main description.
Merge pull request #434 from dhermes/fix-readme-for-pypi

Fixing README.rst to render correctly on PyPI.
Adding PyPI badge to README.
Merge pull request #441 from dhermes/add-pypi-badge

Adding PyPI badge to README.
Adding a non-protobuf allocate_ids method on Dataset.

Partially address #336.
Stash; regression fails.