Vendor GYP and libuv into the repo.

Instead of dynamically downloading these as needed during a build, this
checks in those two dependencies directly into the Wren repo. That's a
little lame because users of Wren who aren't building the CLI don't
actually need them, but they aren't too big, so it's not a huge deal.

It makes builds (particularly on Travis) more reliable, because they
don't have to pull down additional content over the network.

deps/libuv/m4/as_case.m4

@@ -0,0 +1,21 @@
+# AS_CASE(WORD, [PATTERN1], [IF-MATCHED1]...[DEFAULT])
+# ----------------------------------------------------
+# Expand into
+# | case WORD in
+# | PATTERN1) IF-MATCHED1 ;;
+# | ...
+# | *) DEFAULT ;;
+# | esac
+m4_define([_AS_CASE],
+[m4_if([$#], 0, [m4_fatal([$0: too few arguments: $#])],
+       [$#], 1, [  *) $1 ;;],
+       [$#], 2, [  $1) m4_default([$2], [:]) ;;],
+       [  $1) m4_default([$2], [:]) ;;
+$0(m4_shiftn(2, $@))])dnl
+])
+m4_defun([AS_CASE],
+[m4_ifval([$2$3],
+[case $1 in
+_AS_CASE(m4_shift($@))
+esac])])
+