Upgrade limesurvey to 3.19.0+191008

Upgrade to 3.17.0+190402

Upgraded to LimeSurvey 3.15.0+181008

The application is not downloaded and stored in git anymore, it will …

…download directly from LimeSurvey git repository

Upgraded to 2.73.1

removed merge conflicts

Merge pull request #12 from whodafly/update-2.67.3

Update LimeSurvey to 2.67.3+170728

Version 2.67

Merge pull request #10 from crramirez/disable_mysql

Allow disabling internal MySql via DISABLE_MYSQL=yes environment vari…

include php5-curl for comfort update