bump version to 0.1.2

Summary:
Important changes in this release:
- fix curl plugin's quote handling (D144)
- support user-defined plugins (D141)

Reviewers: sean

Reviewed By: sean

Differential Revision: https://phabricator.buildinspace.com/D147
update README

Summary:
Get rid of the separate install instructions for python3.3, and add
links at the bottom.

Reviewers: sean

Reviewed By: sean

Differential Revision: https://phabricator.buildinspace.com/D149
add a description in setup.py

Reviewers: sean

Reviewed By: sean

Differential Revision: https://phabricator.buildinspace.com/D148
Debian package release for 0.1.2

Summary: Update `debian/changelog` for Debian package release for 0.1.2.

Reviewers: jacko

Reviewed By: jacko

Differential Revision: https://phabricator.buildinspace.com/D150