Updated version of blender_spring_plugins (https://springrts.com/phpbb/viewtopic.php?t=17026), unmaintained since Blender 2.4.
Since Spring is currently supporting DAE and other formats, there is no point on upgrading the exporters (see https://springrts.com/wiki/TutorialBlenderWorkFlow).
To install this add-on, go to "File -> User Preferences..." Then select the "Add-ons" tab, and press "Install from File...", choosing the Python script. Remember to activate the addon.
Enjoy it!