[issue-202] extension support as Bottle plugin

[polamayster]

Issue #, if available:
#202
Description of changes:
Added support for Bottle as a plugin

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-io]

Codecov Report

Merging #204 into master will increase coverage by 0.29%.
The diff coverage is 96.82%.

@@            Coverage Diff             @@
##           master     #204      +/-   ##
==========================================
+ Coverage   83.92%   84.21%   +0.29%     
==========================================
  Files          77       78       +1     
  Lines        3004     3067      +63     
==========================================
+ Hits         2521     2583      +62     
- Misses        483      484       +1

Impacted Files	Coverage Δ
aws_xray_sdk/ext/bottle/middleware.py	96.82% <96.82%> (ø)
aws_xray_sdk/core/models/entity.py	92.36% <0%> (+0.69%)	⬆️

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[polamayster]

reason for build fail: aio-libs/aiobotocore@01269ab#diff-ed4c34632c864bc20155bf0c714ee987L86

[bhautikpip]

Yeah we already have a PR ready to fix this (#205). So once we merge it this should be good.

[bhautikpip]

Looks good!

[polamayster]

@bhautikpip is it Ok that I can't see my contribution here https://github.com/aws/aws-xray-sdk-python/graphs/contributors?

[bhautikpip]

Looks like I can see you in the contributor list. (scroll down a bit)

[polamayster]

it's previous small pull request, not this one