Add 'secure' parameter to OAuthHandler constructor.

Add 'secure' parameter to OAuthHandler constructor.

When 'secure' is True, HTTPS will be used for OAuth requests being sent to Twitter.
This only applies to the get token, authorize, and get access token requests. API
requests will not use HTTPS unless the API object also has 'secure' set to True in
its constructor.

Example:
auth = OAuthHandler(token,secret,secure=True)  # use HTTPS for OAuth setup

api = API(auth)  #  will NOT use HTTPS
api_https = API(auth, secure=True)  # will use HTTPS for API requests.

Signed-off-by: Joshua <jroesslein@gmail.com>