[fix] TypeError: host is an invalid keyword argument for this function
I'm confused -- why is `host` getting used?
 Hum i read the doc too rapidly and confused relatif/absolute path. please discard this PR. sorry for the noise.

Was trying to fix this kind of error

```
self = <peewee.SqliteDatabase object at 0x7fc15db82c90>
database = 'tmp/file.db', kwargs = {}

def _connect(self, database, **kwargs):
>       conn = sqlite3.connect(database, **kwargs)
E OperationalError: unable to open database file
```

but the doc is right. furthermore, this fix doesnt cover the use case (absolute path...)

Try to fix this:

```
self = <peewee.SqliteDatabase object at 0x7f79bbfcf950>, database = ':memory:'
kwargs = {'host': file.db'}

def _connect(self, database, **kwargs):
>       conn = sqlite3.connect(database, **kwargs)
E TypeError: 'host' is an invalid keyword argument for this function
```
