Correct capitalization for pypi package names

Signed-off-by: Michal Čihař <michal@cihar.com>

requirements-optional.txt

@@ -2,5 +2,5 @@
 pyuca>=1.1
 pyLibravatar
 pydns
-babel
+Babel
 Mercurial>=2.8

requirements.txt

 Django>=1.7
 Whoosh>=2.5.2,!=2.6.0
-Translate-Toolkit>=1.10.0
+translate-toolkit>=1.10.0
 lxml>=3.1.0
 Pillow
 python-dateutil