Merge pull request #49 from dwenzel/master

Merge Master version 0.7
version 0.8.0-dev
insert a second backlink
insert a second backlink
insert a second backlink
#52 prepend division by zero
default value of property referrerArguments changed to empty array
debug viewhelper for requestArguments added
condition for back button changed to referrerArguments.arguments. This prevents an error caused by empty argument in link viewhelper, closes #50. Moved back button to a section - DRY
typo in condition removed
Wrong @validate annotations removed

fixes #55
Introduction text added
Merge branch 'documentation' of github.com:dwenzel/placements into documentation
hotfixes merged into dev
travis configuration added
configuration for phpunit tests added
typo corrected
typo corrected
scrutinizer upload deactivated
Update ext_localconf.php

typos corrected, closes #56