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

scripts/slave/recipes/perf/telemetry_harness_upload.expected/basic.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.lkgr",
       "--builder",
       "Telemetry Harness Upload",
@@ skipping 53 matching lines @@
     "cmd": [
       "[SLAVE_BUILD]/src/tools/telemetry/build/generate_telemetry_harness.sh",
       "[TMP_BASE]/telemetry-harness_tmp_1/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip"
     ],
     "name": "create harness archive"
   },
   {
     "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",
       "[TMP_BASE]/telemetry-harness_tmp_1/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip",
       "gs://chromium-telemetry/snapshots/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip"
     ],
     "name": "gsutil upload",
     "~followup_annotations": [
       "@@@STEP_LINK@Telemetry rf27fede2220bcd326aee3e86ddfd4ebd0fe58cb9@https://storage.cloud.google.com/chromium-telemetry/snapshots/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip@@@"
     ]
   },
   {
     "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",
       "gs://chromium-telemetry/snapshots/telemetry-f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9.zip",
       "gs://chromium-telemetry/snapshots/telemetry.zip"
     ],
     "name": "gsutil copy",
@@ skipping 13 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import os, sys@@@",
       "@@@STEP_LOG_LINE@python.inline@from common import chromium_utils@@@",
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@if os.path.exists(sys.argv[1]):@@@",
       "@@@STEP_LOG_LINE@python.inline@  chromium_utils.RemoveDirectory(sys.argv[1])@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   }
 ]