Attr-ize AWSCredentials

[codecov[bot]]

Codecov Report

Merging #58 into master will decrease coverage by <.01%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #58      +/-   ##
==========================================
- Coverage   95.93%   95.93%   -0.01%     
==========================================
  Files          74       74              
  Lines        8883     8881       -2     
  Branches      626      627       +1     
==========================================
- Hits         8522     8520       -2     
  Misses        230      230              
  Partials      131      131

Impacted Files	Coverage Δ
txaws/tests/test_credentials.py	100% <100%> (ø)	:arrow_up:
txaws/ec2/tests/test_client.py	99.67% <100%> (ø)	:arrow_up:
txaws/credentials.py	93.47% <100%> (+0.62%)	:arrow_up:

---

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 5cc7aee...f100651. Read the comment docs.

[Julian]

Hey if you really want it, it's one commit, cherry pick yo :P

[Julian]

Uh although it might actually stack, since I changed the tests to use assertEqual. Yeah who knows.