condition statement and conditions should have different representations

[Nfsaavedra]

Is your feature request related to a problem? Please describe.
Right now the condition statement and its conditions are represented with the same construct ConditionStatement. However, this doesn't allow the distinction between them and sometimes the conditions are used as being the condition statement itself.
For instance:

$php_prefix = $::osfamily ? {
    'debian' => 'php5-',
    'redhat' => 'php-',
}

Only has a ConditionStatement for the first condition and one for the second condition, but it doesn't have a construct for the actual switch statement.

Describe the solution you'd like
We should create a new construct either for the conditions or the switch/if statements.