Re-enable the end-to-end, pipeline, and server benchmarks

[seanmonstar]

This were disabled as part of #2929, since they depended on HttpConnector or Server::bind. The first two are easier than the last:

• benches/pipeline.rs
• benches/server.rs
• benches/end_to_end.rs

[Robertoskr]

I will start with reenabling benches/end_to_end.rs

[seanmonstar]

There's a comment in #2934 about what makes it a little harder, which may help in writing the PR.

[Robertoskr]

I'm a bit new to open source, i did the changes, but need a bit of help for pushing the branch to this repo, when i try to push i get the following error:

Username for 'https://github.com': robertoskr
Password for 'https://robertoskr@github.com': 
remote: Permission to hyperium/hyper.git denied to Robertoskr.
fatal: unable to access 'https://github.com/hyperium/hyper.git/': The requested URL returned error: 403

Do you have any idea ? @seanmonstar @oddgrd
Already checked all my ssh keys, tokens urls etc... Can be anything related to this repo ?

[seanmonstar]

You can click the "Fork" button at the top right of this page, and then you can git remote add your fork, and then push to it. Once you have a branch in your fork, you can make a pull request referencing it.