Update release notes
Silence pyflakes warnings
print_versions and print_heavy functions moved to the tests.common module
always use print_versions when test modules are called as scripts
Imports re-ordering in test modules
Always use the internally defined PyTablesTestCase class
Removed internal MetaPyTablesTestCase

The same features are implemented in modern unittest/unittest2
packages.
common.cleanup code moved to PyTablesTestCase.tearDown
Formatting
Use the skipIf decorator
New implementation of assertWarns
More skipIf
Drop unused tables.tests.common.pyTablesTest function
Updated tables.nodes tests