uwsgiconfig: cleanup report initialization
uwsgiconfig: use optparse for arguments passing

This opens the possibility (if desired) to have multiple options
passed at the same time, the same options repeated, etc...
Also it gives an help for free.
uwsgiconfig: add --verbose switch

Print the whole compilation commandlines

Based on a patch from Jonas Smedegaard
uwsgiconfig: add --debug and --asan options

--debug compiles with debug symbols
--asan adds support for compiling with address sanitizer, see
http://clang.llvm.org/docs/AddressSanitizer.html#usage
Should work with clang and gcc 4.8. Does not find as many issues
as valgrind but having lot less overhead could be enabled in more
situations.

While at it handle --cflags and --build together instead of
duplicating code.
Merge pull request #400 from xrmx/config-cleanup

Some uwsgiconfig.py cleanups