Build modified streamline images

The official image from streamline does not currently work for the arm64
platform. As a temporary measure, the source code and docker build scripts
have been lifted from the official images and are used to build locally.

Some additional modifications are made to reduce overall image size, these
are documented in docker/README.md

docker/streamline-src/public/elite/bootstrap/less/grid.less

@@ -0,0 +1,84 @@
+//
+// Grid system
+// --------------------------------------------------
+
+
+// Container widths
+//
+// Set the container width, and override it for fixed navbars in media queries.
+
+.container {
+  .container-fixed();
+
+  @media (min-width: @screen-sm-min) {
+    width: @container-sm;
+  }
+  @media (min-width: @screen-md-min) {
+    width: @container-md;
+  }
+  @media (min-width: @screen-lg-min) {
+    width: @container-lg;
+  }
+}
+
+
+// Fluid container
+//
+// Utilizes the mixin meant for fixed width containers, but without any defined
+// width for fluid, full width layouts.
+
+.container-fluid {
+  .container-fixed();
+}
+
+
+// Row
+//
+// Rows contain and clear the floats of your columns.
+
+.row {
+  .make-row();
+}
+
+
+// Columns
+//
+// Common styles for small and large grid columns
+
+.make-grid-columns();
+
+
+// Extra small grid
+//
+// Columns, offsets, pushes, and pulls for extra small devices like
+// smartphones.
+
+.make-grid(xs);
+
+
+// Small grid
+//
+// Columns, offsets, pushes, and pulls for the small device range, from phones
+// to tablets.
+
+@media (min-width: @screen-sm-min) {
+  .make-grid(sm);
+}
+
+
+// Medium grid
+//
+// Columns, offsets, pushes, and pulls for the desktop device range.
+
+@media (min-width: @screen-md-min) {
+  .make-grid(md);
+}
+
+
+// Large grid
+//
+// Columns, offsets, pushes, and pulls for the large desktop device range.
+
+@media (min-width: @screen-lg-min) {
+  .make-grid(lg);
+}