Add support for exclude filters in package installation

sys/apps/package.lua

@@ -78,6 +78,19 @@ local function install(name, isUpdate, ignoreDeps)
 	local packageDir = fs.combine('packages', name)
 
 	local list = Git.list(manifest.repository)
+
+	-- apply exclude filters from manifest
+	if manifest.exclude then
+		for path in pairs(list) do
+			for _, pattern in ipairs(manifest.exclude) do
+				if path:match(pattern) then
+					list[path] = nil
+					break
+				end
+			end
+		end
+	end
+
 	-- clear out contents before install/update
 	-- TODO: figure out whether to run
 	-- install/uninstall for the package