Merge pull request #2 from libhurl/pasi

Some changes to make the code compile without warnings under Mac OS X + ...
Fixed a lot of clang compiler warnings.
Fixed a lot of sign warnings.
Added eclipse project files to .gitignore.
Changed compiler to LLVM clang in Makefile. Also kept old GCC line.
Fixed many LLVM warnings.
Repalced log_debug with hurl_debug function.
Changed back to GCC in Makefile -- too many linker issues with clang.
Added first basic example showing how to use hooks in hurl.
Fixed return value
Tiny tweaks: cleaning up one warning, clarifying example instruction