Fix «request», «sync» and «error» events documentation.

* signatures had wrong number of parameters;
* it was not documented that «error» is fired by fetch, sync and destroy methods.
Merge pull request #2875 from kmike/events-doc-fix

Fix «request», «sync» and «error» events documentation
Move favicon.ico to root directory so it shows up on all pages. Closes #2883
Shim for AMD underscore test dependency to export _ object
remove shadowed _. Use only the UMD loader for deps
copy most recent qunit fixtures from test/index.html so tests pass
Merge pull request #2885 from akre54/amd-exports-underscore

Fix for shadowed _ dep and broken AMD tests