Installation should not require Cython

pysam already follows the recommendation by Cython developers not to
require Cython to be installed and to instead distribute the compiled C
files, as recommended here:
http://docs.cython.org/src/reference/compilation.html#distributing-cython-modules

Currently, since an install_requires directive containing Cython is passed
to setup(), Cython will always be installed when running 'python setup.py
install' or 'pip install pysam'. This commit removes 'install_requires'.
added get_libraries
refactoring: Tabixfile to TabixFile, etc
added samtools 1.1 and htslib 1.1
added samtools 1.1 to .travis
issue #42 - skip tests requiring internet if no internet present
issue #43 - writing uncompressed BAM output now works
pep8 changes
better tests for malformatted gtf files
added missing unit test files
bugfix in field length test
removed byte strings
fix wrong flag size, closes #49
Merge branch 'pysam-0.8.1' of github.com:pysam-developers/pysam into pysam-0.8.1
Merge pull request #50 from cmclean/master

Raise ValueError when iteration hits truncated line rather than silently exiting
Merge branch 'master' of github.com:pysam-developers/pysam into pysam-0.8.1
bugfix - char from temporary string object
added unit tests for testing different region strings
CL tag consumes until end of line, fixes #39
added build information to faq.rst, closes #37