Fixes #460: Do not show variants by default in spack find.

This does two things:

1. By default `spack find` no longer shows variants.  You have to
   supply `-v` to get that

2. This improves the `colify` implementation so that it no longer pads
   the rightmost column.  This avoids the issue where if one spec was
   too long in the output, *all* specs would have space padding added
   to that width, and it would look like the output of `spack find`
   was double spaced.  This no longer happens -- the one bad line
   wraps around and the other lines are now single-spaced when you use
   `-v` with boost.

lib/spack/llnl/util/tty/colify.py

@@ -198,8 +198,13 @@ def colify(elts, **options):
         for col in xrange(cols):
             elt = col * rows + row
             width = config.widths[col] + cextra(elts[elt])
-            fmt = '%%-%ds' % width
-            output.write(fmt % elts[elt])
+            if col < cols - 1:
+                fmt = '%%-%ds' % width
+                output.write(fmt % elts[elt])
+            else:
+                # Don't pad the rightmost column (sapces can wrap on
+                # small teriminals if one line is overlong)
+                output.write(elts[elt])
 
         output.write("\n")
         row += 1