Prepare the v1.6.0 release

There have been many changes since v1.5.0 that need to be documented in the README:

• Junit Support (add value in reporters list)
• HOCON file type
• ENV file type support
• Support mixed and upper case file extensions (i.e. .TOML and .Toml)
• Added groupby functionality for JSON and Stdout reporters
• Added the ability to produce a file from the reporter
• Optimized element lookup in the fsfinder to improve performance by 30-50%
• Support for the --quiet flag
• Update the archlinux PKGBUILD