ace.js: use URL encoding when building an URL via string concatenation
ace.js: use URL encoding when building an URL via string concatenation

Not performing encoding/decoding when traversing logical domains is a security
risk.
String concatenation is not great, too, but this change is just focused on
allowing the implementation of skin support.

joequant/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,aptivate/etherpad-lite,lpagliari/etherpad-lite,lpagliari/etherpad-lite,joequant/etherpad-lite,ether/etherpad-lite,aptivate/etherpad-lite,joequant/etherpad-lite,University-of-Potsdam-MM/etherpad-lite,aptivate/etherpad-lite,ether/etherpad-lite,lpagliari/etherpad-lite,storytouch/etherpad-lite,storytouch/etherpad-lite,University-of-Potsdam-MM/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,joequant/etherpad-lite,aptivate/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,storytouch/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,ether/etherpad-lite,University-of-Potsdam-MM/etherpad-lite,lpagliari/etherpad-lite,University-of-Potsdam-MM/etherpad-lite