Feature and fix

This adds the feature requested in wswebcreation/webdriver-image-comparison#6 including:

• simplify local config
• add extra test instances for sauce chrome
• add new tests

Last but not least it holds a fix to not always do the customerCSS call that caused issues on FireFox

Contains:

• Merge pull request #9 from wswebcreation/feat/fix-feature df330c6
• feat: prepare to use the latest version of webdriver-image-comparison to use the new formatImageName options d7f216a
• feat: add extra formatImageName options d3a0e12

v1.3.0...v1.4.0