* Allow arbitrary attributes to be added to commands

I still don't approve adding type info back into commands, so
I decided to use this solution for allowing arbitrary attributes to be
added to commands.

Add attributes property to ParameterBuilder

Add Attributes properties to info types

* Why on earth git

* Add using for system so that Attribute can be used

* C#7 features in commands, CommandInfo in ModuleBase

* Update TypeReaders with C#7 features and IServiceProvider

* Add best-choice command selection to CommandService

* Normalize type reader scores correctly

* Fix logic error and rebase onto dev

* Change GetMethod for SetMethod in ReflectionUtils

Should be checking against setters, not getters

* Ensure args/params scores do not overwhelm Priority

* Remove possibility of NaNs

For a command to use the DefaultRunMode, it must now have it's RunMode set to RunMode.Default (this is the default value on CommandAttribute now).

This adds an (optional) CommandServiceConfig, as well as a DefaultRunMode for commands.

This resolves #368 (for commands where a RunMode is not explicitly specified, a custom default value should be used)

In theory this should just work, more testing is needed though

Right now commands require a module before they can be created;
I'm looking to remove this in the future.