Remove Python 2.6 and Python 3.3 from Travis
Remove Python 2.6 and Python 3.3 from Travis

Deprecate these version of Python. Stop testing on Travis-CI.

FrancescAlted/PyTables,avalentino/PyTables,PyTables/PyTables,PyTables/PyTables,FrancescAlted/PyTables,avalentino/PyTables,avalentino/PyTables,PyTables/PyTables,FrancescAlted/PyTables