Added autotools support
Added PF_RING support
Use passivedns version string defined in configure.ac
Print PF_RING version if PF_RING is used
Minor fix to PF_RING code
Code cleanup

Improved consistency, indentation and spell check.
Modified .gitignore to ignore autotools files
Fixed typo in configure.ac
Merge pull request #37 from thus/master

PF_RING and autotools support