support different release channels
Merge branch 'master' of https://github.com/passerellesnumeriques/Students-Database into dev
update deployment script to be able to generate for different release channels
check channel before to install an update
fix choice of channel
fix installer
add tags #CHANNEL_STABLE and #CHANNEL_BETA to be able to have different versions of code depending on the channel
fix deployment script
fix deployment
Merge branch 'master' of https://github.com/passerellesnumeriques/Students-Database into dev

Conflicts:
	deploy/version_and_path_form.php
SQLQuery for production: avoid WHERE IN () or insert nothing. Keep it for development, to force developers to avoid unuseful database requests, but avoid problems in production if ever some checks are missing.
improve checksum calculation
deploy: generate md5 file, so we can switch to md5 only and remove checksum in the next releases
replace usage of checksum by md5
Merge pull request #20 from passerellesnumeriques/dev

0.1 ready to test