Update download script to add parallelism, correct locking, and specific version support. (#291)

Update download script to add parallelism, correct locking, and specific version support.

Add support for provided plugins.
diff --git a/install-plugins.sh b/install-plugins.sh
index e1150fc..f5b4b1a 100755
--- a/install-plugins.sh
+++ b/install-plugins.sh
Binary files differ