Added a httpbin & requestbin testing pages and modules

[powdermnky007]

Thorough and easy to read/understand httpbin and requestbin examples.
I have pretty good looking excel sheet layout, but unfortunately there is no way to send those over without replacing your entire VBA-Web - Example.xlsm file. I have added lots of comments in various places to that file, to further my understanding of how it works. And, while helpful to me, I'm sure you would not want them.

HttpbinSheet
In cell B1, type one of the following commands.
get?show_env=1
get
basic-auth/user/passwd
digest-auth/auth/user/passwd
post (If posting, type your post data into cell B2.)

RequestbinSheet
enter the data you wish to post in cell B1
enter your custom requestb.in URL in cell E5 - Example: 2la2v91

[powdermnky007]

There are a few extraneous commits in here. This is my first time making a pull request on github and I had some issues figuring out how everything worked. I apologize for that.

[powdermnky007]

I also intended to submit the DigestAuthenticator fix as a separate commit, but it got automatically pulled into my existing pull request. :\