Support for lower camel case

[pabloh]

dry-inflector lacks support for lower case camel case conversion like ActiveSupport has, this would useful to have when generating strings for JSON attributes names.

inflector = Dry::Inflector.new

inflector.lower_camelize("first_name") # => "firstName"
inflector.lower_camelize("name") # => "name"

# Or maybe:

inflector.camelize("first_name", lower: true) # => "firstName"
inflector.camelize("name", lower: true) # => "name"

[pabloh]

Copied from Ptico/flexus#3, so we can keep discussing this feature here.