Feature HTTP parser

[iboukhss]

Closes #10, closes #18, closes #20

Lot of work here, trying to do the right thing

[iboukhss]

I added a new HttpParser class

The interface is as follows:

class HttpParser {
    void feed_data(const char* buf, size_t n);
    size_t slurp_data(char* buf, size_t n);
};

The basic idea is to "feed" all data we receive from sockets to the parser, once enough data has been "fed" to the parser, we can retreive either a full HttpRequest or an error.

The parser will also be able to decode chunked encoding in the future, this is why all data must pass through it.

When we need to, we can retreive data from the parser with the function slurp_data() which is basically just like another read/write abstraction.

I added some basic unit tests for request line parsing, like this: GET /index.html HTTP/1.1\r\n

The main logic has alson been changed quite a bit. I will clean it up later or maybe add comments to explain in more detail.

[StokesAsselborn]

Webserver crashes when running and you visit http://localhost:8080

[StokesAsselborn]

As discussed, the router needs to be fixed in order to test this PR.

The overall logic of the parser looks ok. Refinement can be done later.

[iboukhss]

Merging, I think this is good for now..