Issue #6 last releases DbalGateway cross database version
- doc/Installation.md Added autoincrement id to releases table, added
index byCookie
 - DabalGateway added ::insertRelease, ::updateRelease,
::getReleasesIdWhereDateAndUsernameAndIpAddressAndCookie
	::insertOrUpdateRelease now calls getReleaesId, insert or update
functions
 	::isUserReleasedOnAddressFrom, ::isUserReleasedByCookieFrom now select
max(releasedAt) so that race conditions will not affect the outcomes