first implementation of installer, not yet finished
refactor update code: move static methods into own helper class

cleans Kwf_Update class as that's the update script itself
refactor update, siplifies setup usage of updates
refactor update running: create runner class

simplifies usage, especially removes all those boolean parameters
use update runner directly
remove public static method, not needed

has been used ages ago by a import script, which now just called update as own process
remove clear-view-cache parameter, this is unused and should not be used

because it dosn't delete memcache and so we will have old entries in memcache
rename method
refactor writing of already executed update scripts
move checkSettings into own method that allows better error handling
add verbose parameter, off by default
remove support for multiple databases, this is not used
simplify code
show progress bar while updating
less output while executing updates
if not verbose (executed in json controller) discard output from update script
simplify by not using _executeUpdatesAction for checkSettings
output error summary after executing scripts
improve update output
add posibility for update scripts to have multiple steps for progress bar