Fix build download issues due to proxies.

1. When using the default proxy settings derived from http*_proxy, no_proxy
   environment variables, attempting to use httplib2 to socket connect over
   an http connection will fail due the blocking of connect over http due
   to the recommended acl settings in a Squid proxy. See
   http://code.google.com/p/httplib2/issues/detail?id=228
   Work around this by using socks.PROXY_TYPE_HTTP_NO_TUNNEL for http
   connections. This is not a complete solution since using
   socks.PROXY_TYPE_HTTP_NO_TUNNEL still results in an x-squid-error:
   ERR_INVALID_URL 0 error.

2. Work around #1 by forcing download urls to https.

3. Prevent abnormal termination of wptmonitor.py by catching
   exceptions in download_build when non builds are downloaded and
   application.ini is not available to be parsed.