- allow the script to be run from anywhere and not interfere with loc…

…al files

- add detection for git-lfs in the local environment
- at script exit/termination, remove the temporary build folder
- removed hardcoded references to 'piwik' using the current flavour version
- when fetching tags, fetch everything and prune old references too
- when compressing in zip format apply maximum compression (-9)
- fixed an issue where SHA1 wouldn't be displayed in email template
- added SHA512 to email template
- related to #62