Upgrade to Pylint1.4

### Motivation
The latest version of [pylint](https://pypi.python.org/pypi/pylint) is out and ships with some nice new features, such as support for multicore processing, and checkers for Python3-compatible syntax and semantics.

### Changelog
* Update installed version of `pylint` to `1.4.0`.
* Update configuration file (this was done by running `pylint --generate-rcfile` and merging the old and new file).
* Remove version constraint on `astroid`; the issue is now handled via the configuration file of `pylint`.
* Suppress error messages from new checkers; we will deal with them one at a time in future PRs.