retain user email if login fails
prevent from possibly commenting multiple time by hiding the submit button (disabling would not work)
fix category pre-selection when writing a new post for a category
Merge pull request #221 from jsh-c/feature-retain-email-when-login-failed

retain user email if login fails
Merge pull request #224 from jsh-c/fix-category-pre-select-for-new-post

fix category pre-selection when writing a new post for a category
use data-disable-with; remove spinner
Merge pull request #223 from jsh-c/prevent-commenting-multiple-times

prevent from possibly commenting multiple time by hiding the submit butt...