Fix dynamic import of http.client

[thopre]

Summary

Contrary to import, importlib.import_module returns the specified
package or module while import returns the top-level package or
module and is thus what http would be bound to when importing
http.client. This commit fixes the import of http.client so that the
http module is bound to the http variable. Without this change LNT
crashes when receiving an HTTP response not between 200 and 400 (not
included).

[cmatthews]

Thanks!

lnt/lnttool/admin.py

 #!/usr/bin/env python
 from future import standard_library
 standard_library.install_aliases()
 import click
 from importlib import import_module
 from .common import submit_options
 
 
 def _load_dependencies():
     global yaml, sys, requests, json, os, http
     yaml = import_module('yaml')
     sys = import_module('sys')
     requests = import_module('requests')
     json = import_module('json')
     os = import_module('os')
-    http = import_module('http.client')
+    http = import_module('http')
+    import_module('http.client')
 
 
 def _error(msg):
     sys.stderr.write('%s\n' % msg)
 
 
 def _fatal(msg):
     _error(msg)