added aspects and crops to the dummy app
aspect can either be a symbol or a string
url can receive width, height and aspect as argument to return the correct url
added tests database for travis to work
updated gems and ruby version and tests are working now
fixed url return from code review
added download to true tests and refactor assocation methods fix #19
Merge pull request #29 from BenjaminMedia/features/image_url_with_custom_params

Features/image url with custom params