fix(docs): fix issues with local builds

[layershifter]

Fixes #3095. Contains multiple fixes:

• gulp-example-source: cache all sources, to all will be written to exampleSources.json
• gulp docs: fix paths on Windows, now chockidar will watch correctly, Issue with absolute path under windows 10 paulmillr/chokidar#668 (comment)
• ComponentExample.js: update componentWillReceive props to listen for changes in sources

/cc @levithomason

[codecov-io]

Codecov Report

Merging #3098 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3098   +/-   ##
=======================================
  Coverage   99.92%   99.92%           
=======================================
  Files         163      163           
  Lines        2739     2739           
=======================================
  Hits         2737     2737           
  Misses          2        2

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[levithomason]

Works perfect, thank you!

[levithomason]

Released in [email protected].