Implement __call__ for @spool* decorators.

Also removed duplicate code.
Merge pull request #316 from anaconda/spool-decorator-call

Implement __call__ for @spool* decorators.
Fix GCC on Darwin for Python 3.

distutils.sysconfig.get_config_var('CC') returns the compiler used to
build Python, which may be not installed on the system where uWSGI is
being built.

In my case, I grabbed Python 3.3.2 from python.org: it was apparently
compiled with 'gcc-4.2', but my system only has 'gcc' (symlink) and
'llvm-gcc-4.2'.  This change tries to detect this situation (only on
Darwin) and sets GCC to 'llvm-' + compiler returned by sysconfig.
Merge pull request #317 from anaconda/fix-gcc-darwin-llvm

Fix GCC on Darwin for Python 3.
better compiler detection
added seturi and setpathinfo routing actions
Create logo_uWSGI.svg
varios osx build workaround
fix infinite loop in coroae/psgi

Perl PSGI app infinite loops since f20213ff10d1980a97c5c72c2e56044a05f21f8c

Looking at that change, other loop termination conditions are '<= UWSGI_OK'.
Using gdb to inspect the app while looping shows thats ->request is returning
UWSGI_OK in this case. However, the numeric value of this is zero, so we
never exit the for(;;) loop.

Cargo culting loop escape conditions from core/async.c (or gevent/gevent.c)
fixes the inf loop for psgi/coroae.
Merge pull request #323 from jbert/master

Fix infinite loop in psgi/coroae
fixed #324
fixed #321
better clang detection
added --add-cache-item
added router_xmldir plugin
fixed xclient
another attempt to fix xclient
improved xclient
updated gemspec
added setscheme routing action