add encode-decode middleware - fixes #111

[dselivanov]

add encode-decode middleware - fixes #111 add gzip middleware example - fixes #112

[codecov[bot]]

Codecov Report

Merging #114 into dev will decrease coverage by 0.06%. The diff coverage is 0%.

@@            Coverage Diff             @@
##              dev     #114      +/-   ##
==========================================
- Coverage   89.85%   89.78%   -0.07%     
==========================================
  Files          26       26              
  Lines        1301     1302       +1     
==========================================
  Hits         1169     1169              
- Misses        132      133       +1

Impacted Files	Coverage Δ
src/url_encode.cpp	0% <0%> (ø)	:arrow_up:
src/url_decode.cpp	0% <0%> (ø)	:arrow_up:

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[dselivanov]

This also fixes issues found during checks on windows. Namely now we are dealing with http dates at R level (due to the lack of support std::get_time, std::put_timewith g++ < 5) and URL encoding and decoding (for some reason tests fail on windows).