Adding more options for pygments syntax highlighting

This change allows users to specify a lot more options for rst code blocks, I have added the majority of the available pygments options to the list.

The test suite passes clean in 2.7 and has two failures in 3.3 but those seem unrelated to this change: the failures are in test_french_locale and test_turkish_locale with a special character comparison failure in each.

FAIL: test_french_locale (pelican.tests.test_utils.TestDateFormatter)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "......../pelican/pelican/tests/test_utils.py", line 376, in test_french_locale
    utils.strftime(self.date, 'date = %A, %d %B %Y'))
AssertionError: 'date = Mercredi, 29 aoÃ»t 2012' != 'date = Mercredi, 29 août 2012'
- date = Mercredi, 29 aoÃ»t 2012
?                       ^^
+ date = Mercredi, 29 août 2012
?                       ^


======================================================================
FAIL: test_turkish_locale (pelican.tests.test_utils.TestDateFormatter)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "................/pelican/pelican/tests/test_utils.py", line 404, in test_turkish_locale
    utils.strftime(self.date, 'date = %A, %d %B %Y'))
AssertionError: 'date = Ã\x87arÅ\x9famba, 29 AÄ\x9fustos 2012' != 'date = Çarşamba, 29 Ağustos 2012'
- date = ÃarÅamba, 29 AÄustos 2012
?        ^^  ^^          ^^
+ date = Çarşamba, 29 Ağustos 2012
?        ^  ^          ^

  py27: commands succeeded
ERROR:   py33: commands failed