Knob to modify dict alignment

PyCharm support the following formatting configuration for dicts:

Original:
```
{"green": 42, "eggs and ham": -0.0e0}
```

Dict alignment: align on value
```
{
"green": 42,
"eggs and ham": -0.0e0,
}
```

Dict alignment: align on colon
```
{
"green" : 42,
"eggs and ham": -0.0e0,
}
```

A knob to modify this setting in yapf would be great, and would prevent the yapf / PyCharm style formatting loop I've found myself in.