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

scripts/slave/recipes/skia/skia.expected/Test-Android-NexusPlayer-PowerVR-x86-Debug.json

 [
   {
     "cmd": [
       "git",
       "fetch"
     ],
     "cwd": "[SLAVE_BUILD]/skia",
     "name": "git fetch"
   },
   {
@@ skipping 222 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 103 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/skimage/input/*",
       "[SLAVE_BUILD]/images"
     ],
@@ skipping 167 matching lines @@
     "env": {
       "ANDROID_SDK_ROOT": "/home/chrome-bot/android-sdk-linux",
       "SKIA_ANDROID_VERBOSE_SETUP": "1"
     },
     "name": "pull /storage/emulated/legacy/skiabot/skia_dm"
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]/scripts/slave/recipe_modules/skia/resources/upload_dm_results.py",
+      "RECIPE_MODULE[skia]/resources/upload_dm_results.py",
       "[SLAVE_BUILD]/dm",
       "164710",
       "Test-Android-NexusPlayer-PowerVR-x86-Debug",
       "5",
       "",
       "[SLAVE_BUILD]/skia/common/py/utils"
     ],
     "cwd": "[SLAVE_BUILD]/skia",
     "name": "Upload DM Results"
   },
@@ skipping 54 matching lines @@
   {
     "cmd": [
       "/home/chrome-bot/android-sdk-linux/platform-tools/adb",
       "-s",
       "8AB5139A",
       "wait-for-device"
     ],
     "name": "wait for device 8AB5139A (3)"
   }
 ]