Singularity 0.6.1

Changes in 0.6.1

This is a bug fix release.

Check out the 0.7.1 milestone to see bugfixes in detail. (Changes for 0.6.1 are the same as 0.7.1)

• #1034 Change package.json 'vex' dependency to 'vex-js'
• #1049 Don't set shell if arguments list is empty, ability to override shell
• #1050 Add polyfills for Object.assign and Promise