Fix path encoding

[mkistler]

The PR changes the way we handle path parameters. Path parameters are now encoded individually before substituting into the URL, so that all "special" characters (including "#" and "/") are percent-encoded in the resulting URL.

The PR also changes the lint script to lint the examples, and fixes lint all the lint errors/warnings in the examples.

Fixes #304

[codecov-io]

Codecov Report

Merging #305 into v1.0.0 will increase coverage by 0.62%.
The diff coverage is 87.8%.

@@            Coverage Diff             @@
##           v1.0.0     #305      +/-   ##
==========================================
+ Coverage   38.09%   38.72%   +0.62%     
==========================================
  Files          24       24              
  Lines        8187     8292     +105     
==========================================
+ Hits         3119     3211      +92     
- Misses       5068     5081      +13

Impacted Files	Coverage Δ
watson_developer_cloud/watson_service.py	82.75% <100%> (+0.14%)	⬆️
watson_developer_cloud/personality_insights_v3.py	44.23% <100%> (+0.15%)	⬆️
...veloper_cloud/natural_language_understanding_v1.py	31.43% <100%> (+0.16%)	⬆️
watson_developer_cloud/tone_analyzer_v3.py	27.88% <100%> (+0.4%)	⬆️
watson_developer_cloud/visual_recognition_v3.py	29.73% <100%> (+0.81%)	⬆️
..._developer_cloud/natural_language_classifier_v1.py	36.97% <100%> (+1.68%)	⬆️
watson_developer_cloud/language_translator_v2.py	53.27% <70%> (+0.38%)	⬆️
watson_developer_cloud/discovery_v1.py	30.01% <84.61%> (+0.91%)	⬆️
watson_developer_cloud/conversation_v1.py	40.82% <88%> (+0.89%)	⬆️

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[germanattanasio]

Thanks for handling this so quickly!