Fix getMethod

In order to make `getMethod` work, `methods` property have to be indexed by method's name. Also added `array_values` to `getMethods` method to save its behaviour.
Method names to lower case

Since method names are case insensitive, convert it to lower case
Added test for ClassReflector::getMethod
InterfaceReflector::getMethods returns methods indexed by name
Merge pull request #22 from ksimka/patch-1

Fix getMethod