BladeSets should be optional

[leggetter]

BladeSets are a concept that have their uses, but aren't required to start of with.

Internally this may mean that there is a default BladeSet that doesn't reside within a bladeset- directory. But for the developer PoV there isn't a BladeSet.

[andy-berry-dev]

#19 contains the discussion about how we'll handle the 'default' bladeset.

As part of this the default for the create-blade command should be to create a blade in the 'default' bladeset. We can't make the middle argument of the current command optional (e.g. brjs create-blade app-name [bladeset-name] blade-name) since its ambiguous whether the third argument is missing or it is intentionally not there.

Given new users (and probably the majority of OSS users) of BRJS won't use bladesets it would seem sensible to make the default to create the blade without the bladeset and provide a flag to specify whether a bladeset should be used. The command would then look like brjs create-blade app-name blade-name [-bset myBladeset].

@dchambers @leggetter @bit-shifter @stevesouth any thoughts on this?