Use rocket syntax rather than javascript inspired colon syntax

The new javascript inspired colon separator syntax for Ruby hashes is nice in some situations, but is often confusing. In javascript it is simply a separator. In ruby it is both a separator and an indicator of type. 

Here's the good case:
```ruby
hash = { foo: bar } 
```
A hash with keys that are symbols referencing a variable.

But to reference a value in that hash we must revert to the standard type indicator for symbol:
```ruby
hash[ :foo ]
```
If the hash key is not a symbol then you must use the traditional rocket separator:
```ruby
hash = { 'foo' => bar } 
```
Sometimes you would by happy to use a symbol, but your identifier is not easily converted to a symbol:
```ruby
hash = { foo-ish: bar } # error
```
even though you could make a valid symbol if you used the traditional syntax:
```ruby
hash = { :'foo-ish' =>  bar }
hash = { 'foo-ish': bar } # error
```
This proposed update to the ruby style guide is recommending we use the traditional rocket separator.

Here are some inelegant examples from real code:

```ruby
# do symbols have the colon at the beginning or the end?
render :new, layout: 'mobile'

# some types lead to mixing of separators
render json: { "success" => "true" }

# some strings are difficult to coerce into symbols
{ href: "#", "data-fof-id" => target.id }
relation.where(inviter_id: inviter_id).joins(:invitee).where("users.member" => true).count(:invitee_id)
"X-SMTPAPI" => {category: "activity-digest"}.to_json
html: {"data-modify-action" => :update, style: "display: none"}

# inconsistent for no good reason
gon.rabl :template => 'app/views/command_center/project.rabl', as: :project
```