Remove dependency on pip.main, use subprocess.call instead. Fix #12.

ghpythonremote/_configure_ironpython_installation.py

@@ -1,7 +1,7 @@
 import sys
 import os
-import pip
 import logging
+import subprocess
 from shutil import copy, rmtree
 from .helpers import get_rhino_ironpython_path
 
@@ -16,13 +16,14 @@
 
     # Install the package to Rhino IronPython Users lib
     package_name = 'gh-python-remote'
-    pip_cmd = ['install', '--upgrade', '--target=' + rhino_ironpython_path,
+    pip_cmd = [sys.executable, '-m', 'pip', 'install', '--upgrade',
+               '--target=' + rhino_ironpython_path,
                '--no-binary=:all:', '--no-compile', '--ignore-requires-python',
                '--process-dependency-links',
                package_name, ]
     print('\n\nThis will install ghpythonremote in Rhino IronPython with the command:')
-    print('pip ' + ' '.join(pip_cmd))
-    pip.main(pip_cmd)
+    print(' '.join(pip_cmd))
+    subprocess.call(pip_cmd)
 
     # Get the Grasshopper libraries base dir
     gh_userobjects_path = os.path.join(os.getenv('APPDATA', ''), 'Grasshopper', 'UserObjects')