added factory girl and updated spec_helper
Set up factories for certificates
first tests are passing on the certificate model
updated certificate_spec.rb
Added Date Validation
added spec for rendering right templates depending on passed in  params
added responds to 'set_identifier' spec for Certificate
Merge pull request #4 from AgileVentures/tests

Updates in code
Merge branch 'master' of https://github.com/AgileVentures/certificates into tests