bug fixed Transformation::getParameter

default values are returned if requested value doesn't exist
Corrections in Graph and Xsl

Ternary is removed and code is refactored
Merge pull request #1398 from mbed67/bugfixmb

bug fixed Transformation::getParameter
Fix link to Pro Git [ci skip]
Merge pull request #1399 from randomecho/fix-url-contributing

Fix link to Pro Git
Set up automated release
Merge branch 'develop' of github.com:phpDocumentor/phpDocumentor2 into develop
Swapped out URL to do an auto-push
Upped version number to 2.7.0
Set timeout to 15 minutes instead of 5 and prepare next test
Merge branch 'master' of github.com:phpDocumentor/phpDocumentor2 into develop
Tweaked deployment script