update wkhtmltopdf binary to 0.12.0 version on before_script.sh
move tests from Makefile to run_tests.sh
updated README.rst informations to include a official site of wkhtmltopdf and oficial repository on github
increase version of django-wkhtmltopdf
Merge pull request #45 from luzfcb/update-wkhtmltopdf

Update wkhtmltopdf binary and update README.rst