Adds category on UIImage to create images from views
Refactors OCJiraIssue and OCJiraFeedback

* Moves interaction with the manager inside OCJiraIssue adding the
method 'save:'
Adds method to attach files to issues
Adds id, key and self fields
Updates version
Sets authorization header on manager
Fixes pod spec file

* Path to source
Example project uses local pod
Adds 'attachment' field and sends it
Adds patch to attachments endpoint
Implements 'feedbackWithSummary:description:view:completion' method
Sends feedback with screenshot from example project
Merge branch 'feature/take_screenshot' into develop