Added gems and updated files to upload images

Used homebrew to install imageMagick.  Added two gems: carrierwave and
mini_magick.  Configured the user.rb file and users_controller.rb file
to work with these gems.  Created an AWS account to use Amazon S3.
Modified the posts/show and topics/show and devise/registrations/edit
and application.html.erb to accomodate image uploading.  Tested
uploading an image to my profile successfully.
Can now add an image to a post

Added ability to optionally upload an image to a post, and have that
image displayed through the resize_to_fill method at 300x300 on the
posts/show page, and a thumbnail view on the topics/show page.