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

scripts/slave/recipes/chromium_pgo.expected/full_tryserver_chromium_win_win_pgo.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]\\scripts\\slave\\kill_processes.py"
     ],
     "name": "taskkill"
   },
   {
@@ skipping 341 matching lines @@
     ],
     "env": {
       "GYP_DEFINES": "buildtype=Official chrome_pgo_phase=2 component=static_library fastbuild=0 optimize=max target_arch=ia32 use_goma=0"
     },
     "name": "gclient Runhooks: Optimization phase."
   },
   {
     "cmd": [
       "python",
       "-u",
-      "[BUILD]\\scripts\\slave\\recipe_modules\\pgo\\resources\\increase_pgomgr_stack_size.py",
+      "RECIPE_MODULE[pgo]\\resources\\increase_pgomgr_stack_size.py",
       "[DEPOT_TOOLS]\\win_toolchain\\vs2013_files\\VC\\bin\\amd64_x86"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "increase pgomgr.exe stack size"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]\\scripts\\slave\\compile.py",
       "--target",
       "Release",
       "--src-dir",
       "[SLAVE_BUILD]\\src",
       "--build-tool",
       "ninja",
       "--",
       "chrome"
     ],
     "name": "Compile: Optimization phase."
   }
 ]