CLi bookTester should expose the full explanation

[Ducasse]

we should be able to type

pillar checkers LastPeriodInCaption

and get

  'I''m verifying that caption in figure, math equation or code block either ends with a terminating period or not depending on my configuration.


For example authors may want to detect a missing period as in the following elements:

```caption=''This is the famous missing period''
setX: xInt setY: yInt

	...

![''This is the famous missing period'' ](figures/f.png)

$$%caption=''This is the famous missing period''
\frac{1}{2}
$$

In the pillar.conf file you can add the following key values:
{
"LastPeriodInCaption" : true
}'