Fix misconfigured Python paths in default vimrc

Homebrew Python 2.7 was misconfigured to use the wrong path, and
official Python 2.7 install was configured to set "pythonthreedll"
instead of "pythondll". Fix them.

Fix #803

Author: ychin

src/MacVim/vimrc

@@ -19,7 +19,7 @@ set langmenu=none
 " version. However, following code tries to find a Homebrew, MacPorts or
 " an installation from python.org:
 if exists("&pythondll") && exists("&pythonhome")
-  if filereadable("/usr/local/Library/Frameworks/Python.framework/Versions/2.7/Python")
+  if filereadable("/usr/local/Frameworks/Python.framework/Versions/2.7/Python")
     " Homebrew python 2.7
     set pythondll=/usr/local/Frameworks/Python.framework/Versions/2.7/Python
     set pythonhome=/usr/local/Frameworks/Python.framework/Versions/2.7
@@ -29,8 +29,8 @@ if exists("&pythondll") && exists("&pythonhome")
     set pythonhome=/opt/local/Library/Frameworks/Python.framework/Versions/2.7
   elseif filereadable("/Library/Frameworks/Python.framework/Versions/2.7/Python")
     " https://www.python.org/downloads/mac-osx/
-    set pythonthreedll=/Library/Frameworks/Python.framework/Versions/2.7/Python
-    set pythonthreehome=/Library/Frameworks/Python.framework/Versions/2.7
+    set pythondll=/Library/Frameworks/Python.framework/Versions/2.7/Python
+    set pythonhome=/Library/Frameworks/Python.framework/Versions/2.7
   endif
 endif