Rename buildEditSessionForPath to buildEditSession

Since this is the more external method, having a shorter name
is more convenient. The former `buildEditSession` method took a
Buffer, and is now called `buildEditSessionForBuffer`.

benchmark/benchmark-suite.coffee

@@ -107,7 +107,7 @@ describe "TokenizedBuffer.", ->
     [languageMode, buffer] = []
 
     beforeEach ->
-      editSession = benchmarkFixturesProject.buildEditSessionForPath('medium.coffee')
+      editSession = benchmarkFixturesProject.buildEditSession('medium.coffee')
       { languageMode, buffer } = editSession
 
     benchmark "construction", 20, ->