Changed recipe_modules base paths to be abstract entities in their own right.

scripts/slave/recipes/skia/skia.expected/Perf-Win7-ShuttleA-HD2000-x86-Release.json

 [
   {
     "cmd": [
       "git.bat",
       "fetch"
     ],
     "cwd": "[SLAVE_BUILD]\\skia",
     "name": "git fetch"
   },
   {
@@ skipping 143 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@    print \"%s exists but is not a dir\" % path@@@",
       "@@@STEP_LOG_LINE@python.inline@    sys.exit(1)@@@",
       "@@@STEP_LOG_LINE@python.inline@  os.makedirs(path, mode)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]\\scripts\\slave\\recipe_modules\\gsutil\\resources\\gsutil_wrapper.py",
+      "RECIPE_MODULE[gsutil]\\resources\\gsutil_wrapper.py",
       "--",
       "[DEPOT_TOOLS]\\gsutil.py",
       "--force-version",
       "3.25",
       "--",
       "cp",
       "-R",
       "gs://chromium-skia-gm/playback_42/skps",
       "[SLAVE_BUILD]\\playback"
     ],
@@ skipping 102 matching lines @@
       "ShuttleA",
       "os",
       "Win7"
     ],
     "name": "nanobench"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]\\scripts\\slave\\recipe_modules\\skia\\resources\\upload_bench_results.py",
+      "RECIPE_MODULE[skia]\\resources\\upload_bench_results.py",
       "Perf-Win7-ShuttleA-HD2000-x86-Release",
       "5",
       "[SLAVE_BUILD]\\perfdata\\Perf-Win7-ShuttleA-HD2000-x86-Release\\data",
       "164710",
       "[DEPOT_TOOLS]\\third_party\\gsutil\\gsutil"
     ],
     "cwd": "[SLAVE_BUILD]\\skia",
     "name": "Upload Nanobench Results"
   }
 ]