Modifying the numericTicks algorithm to include the last 'nice' tick

Modifying the numericTicks algorithm to include the last 'nice' tick
(either at range end or just past it).

This has the effect of making a (grid lines, axis label) pair always
show up together or not at all. Previously it was possible to get a
label but no gridline at the edge of the chart.

Squashed commit of the following:

commit 32955f836c3c32c11f009ae250cd35682d641e5c
Merge: d3b7c40 0b99641
Author: Dan Vanderkam <danvdk@gmail.com>
Date:   Mon Sep 16 17:18:40 2013 -0400

    Merge branch 'master' of https://github.com/blindmonkey/dygraphs into 269-end-ticks

commit 0b996410efcb7a53315347c8cea38dc225f069ee
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Mon Sep 16 17:08:36 2013 -0400

    Reverting multi-csv

commit 3f72c23c3ebc23adc64dd2605175ff163491d8e2
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Mon Sep 16 17:07:26 2013 -0400

    Changing it so that the right-most X axis tick isn't displayed, and changing the tests to reflect that

commit 3605ec18fb45718dca3dbd3bfb818adb5acc79eb
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Mon Sep 16 16:40:18 2013 -0400

    Reverting whitespace stuff

commit 11959a26e45be3481425f3ba68d78e63730eab4a
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Mon Sep 16 14:43:41 2013 -0400

    Reverting multiple axes old test

commit 4d91af0850a1fa72f693c497ac62e88e35c505eb
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Mon Sep 16 14:42:56 2013 -0400

    Reverting multiple axes test

commit 40b6ea279591df646f10d3ec44f760a20b42cf8a
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Fri Sep 13 14:14:29 2013 -0400

    Changing layout to not layout ticks whose gridline is slightly offscreen.

commit cec9c2857c3c03b14521ccfb4a44bbb4d7163776
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Thu Sep 12 13:26:12 2013 -0400

    Adding tests for the numeric ticker algorithm change.

commit 106c0318cdf6c763a06545cf25f6ef66084cadf7
Author: Sergey <grabkovsky.s@gmail.com>
Date:   Thu Sep 12 12:16:35 2013 -0400

    Changing numericTicks so that it returns the last nice value that might be just outside the axis