Only check alias when we've got our buffer.

This fixes #53.
Check for alias before calling XTables.final_check_match().
Add tests for matches/targets with aliases.
Merge pull request #55 from ldx/issue53pr

Fix #53
Add more examples to docs.

This fixes #54.
Add Bitdeli badge.
Fix return and argument types for various libiptc API calls.
Merge pull request #59 from radhermit/fix-ctypes

Fix return and argument types for various libiptc API calls.