Merge pull request #69 from mehaase/patch-1

Allow bash script to execute from any directory
diff --git a/bin/protoc-gen-dart b/bin/protoc-gen-dart
index 7b398d0..63570e8 100755
--- a/bin/protoc-gen-dart
+++ b/bin/protoc-gen-dart
@@ -1,2 +1,3 @@
 #!/bin/bash
-dart bin/protoc_plugin.dart -c "$@"
+BINDIR=$(dirname "$(readlink -f "$0")")
+dart "$BINDIR/protoc_plugin.dart" -c "$@"