feat: add headerAlign and bodyAlign

[marswong]

@benjycui refer to ant-design/ant-design#2465, and #137 can be closed.

[coveralls]

Coverage remained the same at 97.326% when pulling 9a3416d on marswong:master into 7b5e1a6 on react-component:master.

[coveralls]

Coverage remained the same at 97.326% when pulling 9589a5e on marswong:master into 7b5e1a6 on react-component:master.

[afc163]

columns={[{
  'align': 'left',
}]}

This will be better.

[marswong]

I thought about this, seperated config is flexible, but uncommon in daily usage.
Such as the statistic data always need a table with unified center-aligned table head and right-aligned table body.
So it may be better to expose a unified config API, and if really needed, users can just set text-align in the column render function, but it's really uncommon

[afc163]

It is a common usage for sepecify align for one column: https://ant.design/components/table/#components-table-demo-bordered So #137 maybe a better solution for it.

[marswong]

Got it.