Next 6.x release

It's time to roll-out 6.x-1.7 version. Because a lot of small fixes been commited

Fix undefined variable notice, #git
#987610 by mikeytown2, hadsie: Fix instantiation in masquerade_init()
backport #1103588 isset()
backport of Issue #1019832 by bdragon: masquerade_user_update doesn't check whether ['masquerade_users'] is set, data loss occurs
Issue #1184996: Fix wrong operator in hook_user('update').
Changed attributes of README to 0644
Issue #1147312 by jason.fisher and andypost: Fix nitice in masquerade_block_1()
Fixed alt_login module integration
Issue #1007052 by andypost: Fixed update function, info file and block caching.