I installed the Intellij Idea 15 IDE, and then tried to install php support for it. For that, I installed the following plugin. The IDE now shows the following error after launch.
Plugin Error Problems found loading plugins: Plugin "PHP" was not loaded: required plugin "com.intellij.css" not installed. Disable PHP Open plugin manager
I downloaded the plugin from here.
The PHP Plugin depends on com.intellij.css which is only included in the Ultimate Edition. There is no support for PHP in the Community Edition