Better organization of the coffeescript code executed when a user clicks on a feed in the sidebar.
Changed the name of the global object that stores global coffeescript variables and functions, from "Application" to "Openreader". This is more descriptive and with less likelihood of a colission.
When the user clicks on a feed in the sidebar, the coffeescript event handler stores in a global object the values (feed id, feed path and folder id) that needs the Unsubscribe button handler to unsubscribe from the feed the user is currently reading.

This replaces the previous design, in which these values were stored in data-* attributes of the Unsubscribe button. Storing values in a global object is cleaner and encourages cleaner code, in this case.
The id of the feed the user is currently reading is passed to the coffeescript handler that handles the "new folder" submit event via a global variable, instead of through data-* attributes in the popup.
Values are passed to the coffeescript that handles submit of the New Folder form through global variables, instead of data-* attributes. This encourages cleaner code.
Data needed for the coffeescript handler of the Refresh button is passed through a global variable, instead of through data-* attributes.
Data necessary for the cofeescript event handler that is triggered when a new folder is added to the dropdown is passed through a global variable, instead of through data-* attributes.

This has caused the desaparition of a data-* attribute in the dropdown markup, which has required a change in an acceptance test (a CSS selector was used that assumed the presence of the removed data-* attribute).
Moved the coffeescript code that enables and disables buttons to their own separate functions.

This leads to a more legible code style.
Moved some repeated cofeescript code to global functions.