Fixed test_12_s_utils

String created as a single string without EOL
Added missing file. Needed for for test_40_sigver.
Merge pull request #138 from tpazderka/FixTests

Fixed test_12_s_utils
Added descriptive text.
Added some extra functionality.
Prevent sigve from leaking file descriptors.

After using open() function it is important to always close the file
handler. There are 3 spots in sigver.py where files were opened and
never closed. Following commit introduces new function 'read_file' that
utilized 'with' keyword, hence ensuring the file will always be closed.
Merge pull request #139 from zaccone/fix-leaking-descriptors

Prevent sigve from leaking file descriptors.
Merge branch 'master' of github.com:rohe/pysaml2
Added some extra functionality.