[ISSUE-FIX] CASE WHEN ELSE END statement

[UniForceMusic]

As a proposed solution to #89

Syntax goes as follows:

// If Else
caseStatement()
    ->when($criteria, $result)
    ->when($criteria, $result)
    ->else($result);

// Switch
caseStatement($expression)
    ->when($expression, $result)
    ->when($expression, $result)
    ->else($result);

This syntax compiles to:

-- If Else
CASE 
    WHEN field = ? THEN ?
    WHEN field = ? THEN ? 
    ELSE ?
END

-- Switch
CASE ?
    WHEN ? THEN ?
    WHEN ? THEN ? 
    ELSE ?
END

NOTE:
Cannot use case() as a function or method name because it's a reserved keyword. That's why it's caseStatement()