Fix @returns.json support for casting response using provided type

[prkumar]

Fix @returns.json to cast JSON response (or field referenced by the key argument) using the type argument when the given type is callable. This restores behavior that was inadvertently changed in v0.9.3.

Example:

  @uplink.returns.from_json(key=("data", 0, "size"), type=int)
  @uplink.get("/users/{user}/repos")
  def get_first_repo_size(self, user):
      pass

assert github.get_first_repo_size("prkumar") == 300

#215

[codecov]

Codecov Report

Merging #229 (15cd1e8) into master (17a6283) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #229   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           44        44           
  Lines         2466      2475    +9     
  Branches       355       358    +3     
=========================================
+ Hits          2466      2475    +9     

Impacted Files	Coverage Δ
uplink/returns.py	100.00% <100.00%> (ø)

---

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 17a6283...15cd1e8. Read the comment docs.