Ensuring we are serializing real Python objects

Trying to json.dump Vim dictionaries fails.

python/ycm/base.py

@@ -41,7 +41,7 @@ def BuildServerConf():
   """Builds a dictionary mapping YCM Vim user options to values. Option names
   don't have the 'ycm_' prefix."""
 
-  vim_globals = vimsupport.GetReadOnlyVimGlobals()
+  vim_globals = vimsupport.GetReadOnlyVimGlobals( force_python_objects = True )
   server_conf = {}
   for key, value in vim_globals.items():
     if not key.startswith( YCM_VAR_PREFIX ):

python/ycm/vimsupport.py

@@ -95,7 +95,10 @@ def LoadDictIntoVimGlobals( new_globals, overwrite = True ):
 
 
 # Changing the returned dict will NOT change the value in Vim.
-def GetReadOnlyVimGlobals():
+def GetReadOnlyVimGlobals( force_python_objects = False ):
+  if force_python_objects:
+    return vim.eval( 'g:' )
+
   try:
     # vim.vars is fairly new so it might not exist
     return vim.vars