Update source_image.rb
add source_image index
Merge pull request #48 from geemus/source_image_index

add source_image index
Merge pull request #49 from DariaNico/master

I added a makeString method to make it print out the string for the weblink to the adoption info
Some about text and links to contributors
Merge pull request #50 from Buddington/master

Added about text & links
Update captioned_image.rb
Merge pull request #51 from DariaNico/master

added to_param method to parameterize the id-title
Add spec for @DariaNico's code
Rework SourceImage#makeString into #adoption_info_url
Add link for adoption_info_url

Closes #13
Use partial for show too