Choose a sensible default value for shots

[josh146]

Currently, the plugin devices have a shot default of 1024, whilst the API has a shot default of 100.

We have several options:

• Keep it as is, to ensure that expectation values have a reduction in variance by default.
• Reduce it to 100 to match the API
• Remove the default altogether, forcing users to explicitly request the number of shots.

I am more in favour of the last option (there is less chance to be 'surprised' if you are forced to state how many shots you want from the outset).

[co9olguy]

Agreed