CaptchaBuilder - added the option to add a custom background image for the captcha
CaptchaBuilder - setting backgroundImages default value to array
CaptchaBuilder - added ignore all effects option
README.md - updated docs, added background images and ignore all effects descriptions
Merge remote-tracking branch 'upstream/master'

Conflicts:
	README.md
Merge pull request #15 from ChessCom/master

Add the option of custom background images for the captcha