Fix custom unofficial build tags

Before: CM_VERSION=11-20131217-UNOFFICIAL"-LegacyXperia"-smultron
After:  CM_VERSION=11-20131217-UNOFFICIAL-LegacyXperia-smultron

Change-Id: Ib9c58b39efc4dc5a51380c647db9f7896e165704
diff --git a/config/common.mk b/config/common.mk
index f1f1211..3016dd5 100644
--- a/config/common.mk
+++ b/config/common.mk
@@ -274,7 +274,7 @@
 
 ifeq ($(CM_BUILDTYPE), UNOFFICIAL)
     ifneq ($(TARGET_UNOFFICIAL_BUILD_ID),)
-        CM_EXTRAVERSION := "-$(TARGET_UNOFFICIAL_BUILD_ID)"
+        CM_EXTRAVERSION := -$(TARGET_UNOFFICIAL_BUILD_ID)
     endif
 endif