add matcher for request headers

[eviltwin]

I needed a matcher for request headers and so I built one that I felt was generic enough to warrant inclusion upstream.

Hopefully the detail that I've added to the README.rst is enough to understand the motivation for how I built it, so I'll avoid repeating myself here.

I'm happy to discuss any changes that you might like in order to have this merged.

[markstory]

Nice work. I only had one small suggestion.

[eviltwin]

Looks like I messed up on the python 2.7 messages - I'll be honest and admit that I typed them manually and didn't bother checking they were right... I'll update them along with the changes requested this evening.

[codecov]

Codecov Report

Merging #407 (fa35c2f) into master (374e605) will increase coverage by 2.17%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #407      +/-   ##
==========================================
+ Coverage   95.59%   97.76%   +2.17%     
==========================================
  Files           4        4              
  Lines        1568     1704     +136     
==========================================
+ Hits         1499     1666     +167     
+ Misses         69       38      -31     

Impacted Files	Coverage Δ
responses/matchers.py	100.00% <100.00%> (+3.79%)	⬆️
responses/test_responses.py	99.12% <100.00%> (+0.59%)	⬆️
responses/__init__.py	98.23% <0.00%> (+5.09%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 374e605...fa35c2f. Read the comment docs.

[markstory]

Looks like there are a few conflicts with one of the other recently merged pull requests. Sorry about that.

[beliaev-maksim]

@eviltwin
just to give you background. I aligned messages for Python 2 and 3 in #403.
Also, reason from matchers propagates now directly to responses without modification

please update the PR according to the logic, you can find implementation details in HEAD of the master

[eviltwin]

Damn, that's what I get for sitting on this for four weeks I guess :)

I'll take a look now :)

[eviltwin]

thanks to both @beliaev-maksim and @markstory for your input 🙂

I've rebased this against master, changed the param name and squashed things together to tidy up the history. Hopefully it now incorporates everything discussed 👍

[beliaev-maksim]

code implementation looks good to me

[wilcoschoneveld]

@eviltwin awesome! thanks for this PR!

@markstory can this be merged?

[markstory]

Thank you 👍