Replacing initscript with atlassians script

the previous init script failed to start on some test systems; This version
is based on the one provided from atlassian via
https://confluence.atlassian.com/display/STASH/Running+Stash+as+a+Linux+service
or directly
https://bitbucket.org/ssaasen/atlassian-stash-lsb-startup-script/src/master/stash
Changing default shell for stash user

according to https://confluence.atlassian.com/display/STASH/Running+Stash+with+a+dedicated+user the stash user must have a login shell (not /bin/false)
Merge pull request #6 from preflightsiren/master

Replacing initscript with atlassians script