Updating @imports to match case of file names.

Updating the @import less statements for reset.less, variables.less,
mixins.less and gfx.less to match the case of the filenames on disk.
This fixes a build problem using lessc on Ubuntu 10.04.

source/less/VMM.Timeline.less

@@ -39,13 +39,13 @@
 ----------------------------------------------------- */
 
 // CSS Reset
-@import "Reset.less";
+@import "reset.less";
 
 // Core variables and mixins
 @import "Font.Default.less";
-@import "Variables.less";
+@import "variables.less";
-@import "Mixins.less"; 
+@import "mixins.less"; 
-@import "GFX.less";
+@import "gfx.less";
 
 // Grid system and page structure
 @import "VMM.Timeline.Core.less";