Update email templates for email on push service with links to commit and repository.

app/views/notify/repository_push_email.html.haml

-%h3 #{@author.name} pushed to #{@branch} at #{@project.name_with_namespace}
+%h3 #{@author.name} pushed to #{@branch} at #{link_to @project.name_with_namespace, project_url(@project)}
 %h4 Commits:
 %ul
   - @commits.each do |commit|
     %li
-      %strong #{commit.short_id}
+      %strong #{link_to commit.short_id, project_commit_url(@project, commit)}
       %span by #{commit.author_name}
       %pre #{commit.safe_message}

app/views/notify/repository_push_email.text.haml

-#{@author.name} pushed to #{@branch} at #{@project.name_with_namespace}
+#{@author.name} pushed to #{@branch} at #{link_to @project.name_with_namespace, project_url(@project)}
 \
 Commits:
 - @commits.each do |commit|
-  #{commit.short_id} by #{commit.author_name}
+  #{link_to commit.short_id, project_commit_url(@project, commit)} by #{commit.author_name}
   #{commit.safe_message}
   \- - - - -
 \