Merge pull request #605 from avelino/master

update Google App Engine docs url
Don't run the twisted reactor if it's already running

This prevents nasty errors when embedding Bottle within twisted apps that already make use of the reactor (and therefore also start it).
Merge pull request #608 from UltrosBot/master

Don't run the twisted reactor if it's already running
Replicate orrection #611 0.12 to master
ResourceWarning: unclosed file <_io.BufferedReader