Add infra recipe module, use for updating Go DEPS

infra/bots/recipes/swarm_RecreateSKPs.expected/Housekeeper-Weekly-RecreateSKPs.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "\nimport sys, os\npath = sys.argv[1]\nmode = int(sys.argv[2])\nif not os.path.isdir(path):\n  if os.path.exists(path):\n    print \"%s exists but is not a dir\" % path\n    sys.exit(1)\n  os.makedirs(path, mode)\n",
       "[CUSTOM_/_B_WORK]",
       "511"
     ],
     "name": "makedirs checkout_path",
@@ skipping 227 matching lines @@
     ],
     "cwd": "[CUSTOM_/_B_WORK]/skia",
     "env": {
       "CHROME_HEADLESS": "1",
       "PATH": "[DEPOT_TOOLS]:%(PATH)s"
     },
     "name": "Recreate SKPs"
   },
   {
     "cmd": [
+      "go",
+      "get",
+      "-u",
+      "go.skia.org/infra/..."
+    ],
+    "env": {
+      "GOPATH": "[CUSTOM_/_B_WORK]/gopath"
+    },
+    "name": "update go pkgs"
+  },
+  {
+    "cmd": [
       "python",
       "-u",
       "\nimport os\nimport urllib2\n\nTOKEN_FILE = '.depot_tools_oauth2_tokens'\nTOKEN_FILE_BACKUP = '.depot_tools_oauth2_tokens.old'\nTOKEN_URL = 'http://metadata/computeMetadata/v1/project/attributes/depot_tools_auth_update_skps'\n\nreq = urllib2.Request(TOKEN_URL, headers={'Metadata-Flavor': 'Google'})\ncontents = urllib2.urlopen(req).read()\n\nhome = os.path.expanduser('~')\ntoken_file = os.path.join(home, TOKEN_FILE)\nif os.path.isfile(token_file):\n  os.rename(token_file, os.path.join(home, TOKEN_FILE_BACKUP))\n\nwith open(token_file, 'w') as f:\n  f.write(contents)\n"
     ],
     "name": "depot-tools-auth login",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@python.inline@@@@",
       "@@@STEP_LOG_LINE@python.inline@import os@@@",
       "@@@STEP_LOG_LINE@python.inline@import urllib2@@@",
       "@@@STEP_LOG_LINE@python.inline@@@@",
@@ skipping 17 matching lines @@
   {
     "cmd": [
       "python",
       "[CUSTOM_/_B_WORK]/skia/infra/bots/upload_skps.py",
       "--target_dir",
       "[SLAVE_BUILD]/skp_output"
     ],
     "cwd": "[CUSTOM_/_B_WORK]/skia",
     "env": {
       "CHROME_HEADLESS": "1",
+      "GOPATH": "[CUSTOM_/_B_WORK]/gopath",
       "PATH": "[DEPOT_TOOLS]:%(PATH)s"
     },
     "name": "Upload SKPs"
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport os\n\n\nTOKEN_FILE = '.depot_tools_oauth2_tokens'\nTOKEN_FILE_BACKUP = '.depot_tools_oauth2_tokens.old'\n\n\nhome = os.path.expanduser('~')\ntoken_file = os.path.join(home, TOKEN_FILE)\nif os.path.isfile(token_file):\n  os.remove(token_file)\n\nbackup_file = os.path.join(home, TOKEN_FILE_BACKUP)\nif os.path.isfile(backup_file):\n  os.rename(backup_file, token_file)\n"
     ],
@@ skipping 17 matching lines @@
       "@@@STEP_LOG_LINE@python.inline@  os.rename(backup_file, token_file)@@@",
       "@@@STEP_LOG_END@python.inline@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]