fix github tests

seems like something changed in the GitHub API, tests occasionally fail with:

```
======================================================================
FAIL [0.774s]: Test the githubfs read function without using the api
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/var/lib/jenkins/workspace/easybuild-framework_unit-test_boegel_test-python24/test/framework/github.py", line 83, in test_read
    self.assertEquals(open(fp, 'r').read(), "this is a line of text\n")
AssertionError: 'this is a line of text\n\n' != 'this is a line of text\n'

----------------------------------------------------------------------
```

This patch should fix that.