IntelliJ modules inherit JDK versions from config

Created by: illuminace

IntelliJ project JDK versions are configurable in the [intellij] section of .buckconfig via jdk_name and language_level. These affect the project-wide versions configured in .idea/misc.xml

JDK versions in .iml module configs, however, are hardcoded to JDK 1.7. This needs to be configurable from somewhere - I've taken it to be the [intellij] configuration section.

i.e. given the following configuration

[intellij]
  jdk_name = 1.8
  jdk_type = JavaSDK
  language_level = JDK_1_8

then the .iml dep

<orderEntry type="jdk" jdkName="1.7" jdkType="JavaSDK" />

should be

<orderEntry type="jdk" jdkName="1.8" jdkType="JavaSDK" />