ng2-smart-table dropdown filter or editor gets bigger than text inputs.

Hi everyone. I'm facing an styling issue on ng2-smart-table.

* [x] bug report
* [ ] feature request
* [ ] question about the decisions made in the repository

### Issue description

When setting.column.filter.type or setting.column.editor.type set to list, the size of dropdown gets bigger than text inputs like image below.

**Steps to reproduce:**
Simply changing type to list like this.

```
settings: {
columns: {
age: {
title: 'Age',
editor: {
type: 'list',
config: {
selectText: 'Select',
list: [
{value: '1', title:'Option 1'},
{value: '2', title:'Option 2'},
{value: '3', title:'Option 3'},
{value: '4', title:'Option 4'},
],
},
}
filter: {
type: 'list',
config: {
selectText: 'Select',
list: [
{value: '1', title:'Option 1'},
{value: '2', title:'Option 2'},
{value: '3', title:'Option 3'},
{value: '4', title:'Option 4'},
],
},
},
},
}
}
```

I fixed this problem using these CSS:
```
.ng2-smart-filter select {
height: calc(2rem + 4px) !important;
padding: 0 10px !important;
}

table-cell-default-editor select-editor select {
height: calc(2rem + 8px) !important;
padding: 0 10px !important;
}
```
and here is the result.

but I'm not sure if it's the best way.

I will be very happy if I know that how can I fix this issue on main project.