Merge branch 'release-1.7.0' into stable

Update CHANGELOG.md

Merge branch 'feature-13' into release-1.7.0

FIX: EMR prices are not kept when computing SPOT instances price #13

Merge branch 'release-1.7.0' into feature-13

[twgit] Init feature 'feature-13': EMR prices are not kept when computing SPOT instances price.

Update dependencies and add Dependency Badge.

Add TOC to README.md.

Merge branch 'feature-16' into release-1.7.0

[twgit] Init release 'release-1.7.0'.

Code quality improvement. #16

FIX EMRInstancePrices bug due to use of deprecated URL. #16

[twgit] Init feature 'feature-16': Amazon pricing schema deprecated.

Merge branch 'release-1.6.0' into stable

Update "Command line options" section of README.md