OTA template configurable + OTA for https enabled

This Pull Request fixes https://github.com/sap-production/OTAService/issues/6.

The xcode-maven-plugin has to generate the correct OTA HTML pages with the alternative referrer solution using javascript.

Furthermore the used template is now configurable from outside. If any issues occur in the future we can simply adjust the template without forcing users to switch to a new version of the plugin.