supports WP 3.9

git-svn-id: http://plugins.svn.wordpress.org/aviation-weather-from-noaa/trunk@907964 b8457f37-d9ea-0310-8a92-e5e31aec5664
Refactor per WordPress coding standards

Replace cURL and allow_url_fopen() with wp_remote_get()
Add check to limit hours before now to 6 in shortcode
Add checks for empty/missing values
Better sanitizing

git-svn-id: http://plugins.svn.wordpress.org/aviation-weather-from-noaa/trunk@953892 b8457f37-d9ea-0310-8a92-e5e31aec5664
Merge branch 'master' of github.com:machouinard/aviation-weather-from-noaa
Add banner