Add allow_extra_spaces option to SpaceBeforeBrace

Enables the `SpaceBeforeBrace` linter to allow extra spaces so that
multiple single line blocks can be aligned for better readability.

Change-Id: I3d12a6db3fd34eab1a6b346034ea71a3f0264566
Reviewed-on: http://gerrit.causes.com/36826
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Extract node_on_single_line helper into Linter

This method was duplicated in two linters. Consolidate it into a helper
in the `Linter` superclass to keep things DRY.

Change-Id: I5aa7d3e8f1bd054df9700086a1fd9a3c4d8a58b5
Reviewed-on: http://gerrit.causes.com/36827
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Reword SpaceBeforeBrace lint description

Alter slightly to refer to the specific curly brace rather than curly
braces in general, and use backticks instead of parentheses to make it
easier to read.

Change-Id: Ia068dae02f5dc6ffae8dea60928bc65ed299f4a0
Reviewed-on: http://gerrit.causes.com/36829
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Rename SpaceBeforeBrace allow_extra_spaces option

`allow_extra_spaces` doesn't properly convey the fact that this option
only applies to single line blocks. Rename it to a slightly more verbose
`allow_single_line_padding` to emphasize this, as well as indicate the
that the extra spaces are meant to serve as visual padding.

Change-Id: I6651ab71448acdba88e5abfe2a2b59d3623c00eb
Reviewed-on: http://gerrit.causes.com/36830
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Add changelog entry for allow_single_line_padding

Change-Id: Iff15ec96f45f97f86c3289561bbf2a3cff7cbe6d
Reviewed-on: http://gerrit.causes.com/36831
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>
Reword spec description to not refer to issue 94

Referring to the issue requires an extra step to understand the test
(visiting the issue page). Rewrite the description to describe the
actual scenario being tested.

Change-Id: Ieec3cd11915b35b0056ac6ca84abf35dd01f580f
Reviewed-on: http://gerrit.causes.com/36828
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>