Created an empty src-gen directory so the xtext code generator runs out of the box

Change-Id: I9c5802b58770b37f51dffd4f7f3f01de114e122e
diff --git a/com.google.eclipse.protobuf/.gitignore b/com.google.eclipse.protobuf/.gitignore
index 6064afa..e3bfd91 100644
--- a/com.google.eclipse.protobuf/.gitignore
+++ b/com.google.eclipse.protobuf/.gitignore
@@ -1,6 +1,5 @@
 /bin
 /model/
-/src-gen/
 /xtend-gen
 /.antlr*.jar
 /plugin.xml_gen
diff --git a/com.google.eclipse.protobuf/src-gen/.gitignore b/com.google.eclipse.protobuf/src-gen/.gitignore
new file mode 100644
index 0000000..1184819
--- /dev/null
+++ b/com.google.eclipse.protobuf/src-gen/.gitignore
@@ -0,0 +1,4 @@
+## The directory src-gen is required to prevent build path errors.
+
+# Ignore everything
+*