Update README.md

Switched method to symlink into git repo to make upgrades easier.
Added docs on reverting and upgrading
Merge pull request #4 from tsaavik/master

I'd like to suggest an alternative install method in readme, to make upgrades easier in the future
onLoad, display tab entered on the location's hash, e.g. #system
include text link to the service on top of every graph, makes page searchable
Merge pull request #6 from stsimb/upstream

onLoad, display tab entered on the location's hash, e.g. #system
Add warnings id to munin-problemview.tmpl as per tabascoterrier comment May 7th
Merged changes by Rauks
Merge branch 'Rauks-master'
Merging Rauks improvements CSS fixes, mobiles fixes etc
Amended README.md to fix paths for reverting back
Merge pull request #7 from jonnymccullagh/master

Get update