Add category order (#2592)

* Add category order

Each category has a new 'priority' attribute. It is used to sort categories in
views. Categories with the same priority are sorted alphabetically. Categories
with no priority are displayed after those with one.

For example, if we have the following categories:
- A (priority: 2)
- B (no priority)
- C (priority: 1)
- D (priority: 2)
- E (no priority)
- F (priority: 1)

They will be displayed in the following order:
- C
- F
- A
- D
- B
- E

See #190

* Shorten help text

It took too much room and will not be so necessary once we have drag &
drop

1 files changed, 2 insertions, 2 deletions

diff --git a/app/Models/Category.php b/app/Models/Category.php
index a0ee1ddaa..a195c88b3 100644
--- a/app/Models/Category.php
+++ b/app/Models/Category.php
@@ -98,14 +98,14 @@ class FreshRSS_Category extends Minz_Model {
 	}
 
 	public function _attributes($key, $value) {
-		if ($key == '') {
+		if ('' == $key) {
 			if (is_string($value)) {
 				$value = json_decode($value, true);
 			}
 			if (is_array($value)) {
 				$this->attributes = $value;
 			}
-		} elseif ($value === null) {
+		} elseif (null === $value) {
 			unset($this->attributes[$key]);
 		} else {
 			$this->attributes[$key] = $value;