Modify setup.py to build protos on Windows

Also change yaml library to one that builds on Windows

setup.py

@@ -23,6 +23,7 @@
 from distutils.command.build import build
 from distutils.command.clean import clean
 from distutils.cmd import Command
+from distutils.spawn import find_executable
 from setuptools import find_packages
 from setuptools import setup
 from setuptools.command.test import test
@@ -63,19 +64,23 @@ def initialize_options(self):
         # Default to /usr/local for Homebrew
         prefix = '/usr/local'
       else:
-        print('Warning: mfg-inspector output is not fully implemented for '
-              'Windows. OpenHTF will be installed without it.')
-        self.skip_proto = True
+        prefix = None
 
-    maybe_protoc = os.path.join(prefix, 'bin', 'protoc')
-    if os.path.isfile(maybe_protoc) and os.access(maybe_protoc, os.X_OK):
+    self.protoc = None
+    if prefix:
+      maybe_protoc = os.path.join(prefix, 'bin', 'protoc')
+      if os.path.isfile(maybe_protoc) and os.access(maybe_protoc, os.X_OK):
         self.protoc = maybe_protoc
-    else:
+      else:
         print('Warning: protoc not found at %s' % maybe_protoc)
         print('setup will attempt to run protoc with no prefix.')
-        self.protoc = 'protoc'
+    if not self.protoc:
+      self.protoc = find_executable('protoc')
+      pc_path = os.path.dirname(find_executable('protoc'))
+      self.protodir = os.path.abspath(os.path.dirname(pc_path) + '/../lib')
 
-    self.protodir = os.path.join(prefix, 'include')
+    else:
+      self.protodir = os.path.join(prefix, 'include')
     self.indir = os.getcwd()
     self.outdir = os.getcwd()
 
@@ -109,6 +114,9 @@ def run(self):
                   '"protobuf-compiler" and "libprotobuf-dev" packages.')
           elif sys.platform == 'darwin':
             print('On Mac, protobuf is often installed via homebrew.')
+          else:
+            print('On Windows, protoc should be installed and added '
+                  'to the path.')
         raise
       except subprocess.CalledProcessError:
         print('Could not build proto files.')
@@ -130,7 +138,7 @@ def run(self):
     'mutablerecords>=0.4.1,<2.0',
     'oauth2client>=1.5.2,<2.0',
     'protobuf>=3.0.0,<4.0',
-    'pyaml>=15.3.1,<16.0',
+    'PyYAML>=3.10,<4.0',
     'pyOpenSSL>=17.1.0,<18.0',
     'sockjs-tornado>=1.0.3,<2.0',
     'tornado>=4.3,<5.0',