WIP allow sorting by integers

This is a POC. If it is seen to be a viable solution I will clean it up :)

DoctrineDBAL does not currently allow sorting on integer properties. This means that when you perform an ORDER BY on a set of numbers the result may be: `10, 100, 1000, 2, 20` etc.

The best solution *would* be to use the `CAST` keyword (e.g. `ORDER BY CAST([sulu:order])`) but CAST will only ever work on static operands (e.g. `CAST('12' AS LONG)`)

This PR separates the property values into three separate columns, `props`, `long_props` and `decimal_props` and orders by all three.

````
SELECT ... WHERE ...  ORDER BY 
CAST(EXTRACTVALUE(n0.long_props, '//sv:property[@sv:name="sulu:order"]/sv:value[1]') AS INTEGER), 
CAST(EXTRACTVALUE(n0.decimal_props, '//sv:property[@sv:name="sulu:order"]/sv:value[1]') AS DECIMAL),
EXTRACTVALUE(n0.props, '//sv:property[@sv:name="sulu:order"]/sv:value[1]')
````

This seems to work.
Columns `prop`, `long_prop` and `decimal_prop` can now all be nullable.