[twgit] Init feature 'feature-doc'.
Add PHPDoc.
minor fix
Adjust estimation of global price with spots instances.
Add API documentation.
Improve compute of size of S3 objects.
Add overview and animated task timeline.
Add README.md and CHANGELOG.md
Move README.md images from /resources to /doc/images.
Merge branch 'feature-doc' into release-1.4.0