added tests to ensure new img tag regex is parsing properly
added tests to ensure new img tag regex is parsing properly

constantcontact/premailer,r-shah/java-premailer-wrapper,r-shah/java-premailer-wrapper,r-shah/java-premailer-wrapper,Guestfolio/premailer,Guestfolio/premailer,ale7714/premailer,PrecisionNutrition/premailer,danimashu/premailer,ale7714/premailer,thebeansgroup/premailer,will-in-wi/premailer,academia-edu/premailer,constantcontact/premailer,ministrycentered/premailer,thebeansgroup/premailer,ministrycentered/premailer,PrecisionNutrition/premailer,danimashu/premailer,will-in-wi/premailer,academia-edu/premailer