Allow `on_client` and related methods to be run in RSpec before(:all) blocks

ATM if you run `on_client`, `mount` and `isomorphic` methods in `before(:all)` blocks they just don't do anything, because the capybara `page` is not loaded yet.

What should happen is that the args to those methods should be queued up and added in a mechanism similar what `before_mount` uses.

A note (that also applies to before_mount) is that if `no_reset` is false, then this action should repeat on each spec, but if no_reset is true, then it should only happen once.

```ruby
before(:all) do
on_client do
puts 'hello world'
end
end
```

if no_reset is true, then 'hello world' will be displayed just once on the client, if no_reset is false then it will be displayed as each spec runs.

NOW... given all this, it would seem that what we really want to do is also make these methods (and before_mount) all available at the spec block level, which would mean that they run in a before(:all) block. So the above could be shortened to

```ruby
on_client do # before(:all) is implicit
puts 'hello world'
end
```