String Formatting and PEP-8 fixes

[vkmrishad]

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation about the functionality in the appropriate .md file
• I have added inline documentation to the code I modified

Short description of what this PR does:

• PEP8 fixes
• String formatting enhancement

If you have questions, please send an email to SendGrid, or file a GitHub Issue in this repository.

[codecov]

Codecov Report

Merging #111 into master will decrease coverage by 24.22%.
The diff coverage is 50%.

@@             Coverage Diff             @@
##           master     #111       +/-   ##
===========================================
- Coverage   91.34%   67.12%   -24.23%     
===========================================
  Files           6        6               
  Lines         289      289               
===========================================
- Hits          264      194       -70     
- Misses         25       95       +70

Impacted Files	Coverage Δ
tests/test_unit.py	69.59% <ø> (-29.61%)	⬇️
tests/test_repofiles.py	100% <ø> (ø)	⬆️
python_http_client/client.py	54.36% <50%> (-23.31%)	⬇️
python_http_client/exceptions.py	73.68% <0%> (-23.69%)	⬇️

---

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[codecov]

Codecov Report

Merging #111 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #111   +/-   ##
=======================================
  Coverage   91.46%   91.46%           
=======================================
  Files           6        6           
  Lines         293      293           
=======================================
  Hits          268      268           
  Misses         25       25

Impacted Files	Coverage Δ
tests/test_unit.py	99.2% <ø> (ø)	⬆️
tests/test_repofiles.py	100% <ø> (ø)	⬆️
python_http_client/client.py	77.66% <100%> (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 a45c299...ed8b8e2. Read the comment docs.

[vkmrishad]

@misterdorm

[vkmrishad]

@misterdorm
Please add available labels and merge this PR

[thinkingserious]

Hello @vkmrishad,

Thanks again for the PR!

It's HACKTOBERFEST! We want to show our appreciation by sending you some special Hacktoberfest swag. If you have not already, could you please fill out this form so we can send it to you? Thanks!

Team SendGrid DX

[vkmrishad]

@thinkingserious @misterdorm
Thank you