Content-Type header parser

[nnsee]

This fixes #257.

Added a spec-compliant (as far as I can tell) header parser for the Content-Type header, specifically in regards to the boundary param. Also added some tests for the new parser and form.nim.

[nnsee]

I don't know why the tests fail. It also fails on devel even without my changes. And the process seems to hang.

[ringabout]

The devel actually passes the tests because circle CI is unused though it still causes failures. I guess there is a loop which causes the hang

[PhilippMDoerner]

Out of curiosity, what blocks this? A fix for the test-suite?

[ringabout]

I think so. Besides, I could merge a workaround PR to replace rfind with find => #260

[nnsee]

I don't think the test suite issue is from my side, try to run the test suite on just the master branch of this repo and see if it exhibits the same behavior, I'm pretty sure it does.

[ringabout]

It seems that #263 the cookie dep causes the hang

[PhilippMDoerner]

I think before I go any deeper into this: I'm happy to do a codereview here, if my style of code that I tend to strive for and find most readable works for y'all.

As in, I am very thankful you took the time to implement this Ras, I'd just love to split a few things out for example to have a few smaller procs that do individual tasks like a "parseMediaType" proc that returns a parsed media-type and media-type start- and end-indexes etc.
My goal there would be that ideally you don't need to know the RFCs to understand the code, the variable names and proc names tell you everything you need while isolating smaller individual tasks.

However, if that looks like it does more work than it's worth I'm happy to drop that.

[ringabout]

Nice work!

[PhilippMDoerner]

Overall, LGTM. A couple suggestions that you can heed if you want to, I'll leave that up to you.

[nnsee]

Thanks for the code review!