Add type and alignment options

[dtamajon]

I propose to add column type and alignment options in "Grid configuration" field for a better grid customization. For a simple example, you could render a column as currency just like:

{
"type": {
"Total": "currency"
},
"alignment": {
"Total": "right"
}
}

This patch is overwritten by #80. In case #80 is accepted, this patch can be dismissed.