[backend] transport link chain in remote_getrev if the expansion failed

Should help with stuck 'service in progress' errors.
[api] Fix ldap incorrect use of 'login' variable
[api] Fix 'user_ldap_strategy.rb' unable to call 'logger.debug' method

make direct call to Rails.logger.debug instead of logger.debug
[dist] Allow overriding initrd without overriding kernel
[webui] Visual improvement to the monitoring page
[webui] fix crash in monitor/old with new rails
[api] support the description of attribute definitions for real

It was there since the beginning, but never finished.
[api] set some default descriptions for the attribute type definitions.

Please, someone, review content and my language of them. Much appriciated!
[api] urgs, revert a typo
[backend] run linking of product trees in background

of bs_repserver when running a binary copy (aka package release).
This avoids timeout errors via the api.