BUG Fix integer check

The previous version did not even pass unit tests
DOC Document xcftool dependency
TST Use travis-ci for testing
TST Forgot to install xcftools in travis build
TST Use pip to install numpy

This should make the tests work on any version of Python.
TST Install numpy with pip

This was supposed to go in the previous commit
DOC Add travis status image
DOC requirements file for rtfd.org
BLD New release 0.2.6

Full ChangeLog
	* Fix hard crash when saving with non-existing file type
	* Fix compilation on MacOS (patch by Alexander Bohn)
	* Add ``verbose`` argument to tests.run()
	* Better error when attempting to save floating point images
ENH Initial support for reading image metadata
TST Use public interfaces in tests
PY3 Compilation fix for Python 3
ENH Write metadata to TIFFs
TST Test writing & reading of metadata
TST Declare version 3.2 & earlier *not supported*
PY3 Fix metadata test on Python 3
ENH Support for reading from in-memory blobs
BUG Fix conversion to greyscale on reading
DOC Document imread_from_blob
TST Fix tests for Python 3

Python 3 needs files to be opened in binary mode or it starts to
interpret them according to an encoding (which we do not want for image
files).