Split up Secure vs Insecure for the requests HTTPAdapters
Use the --trusted-host argument to disable TLS verification as well
Revert "Add option --no-check-certificate to skip ssl cert verification"

This reverts commit 9a9d7acefe2168c84ab135501284b78827ab58b2.

Conflicts:
	pip/cmdoptions.py
Adjust changelog to switch from --no-check-certificate to --trusted-host
Adjust the --trusted-host help option
Adjust tests to compensate for --trusted-hosts
Merge pull request #2237 from dstufft/consolidate-security

Treat HTTP and invalid HTTPS the same