Added footer to read_html

read_html neglected table footers. Although rare, some sites use the footer for data. First time pull request so hopefully not messed up.
you should update `body` inplace via either ` body += [foot]` or `body.extend([foot])`.

When you do this operation:

```python
body = body + [foot]
```

You're actually allocating memory for a new `list` and filling in with the result then assigning the result to the name `body`, whereas when you do

```python
body += [foot]
```
you're only allocating the extra space needed to append `foot` to the end of `body`. Additionally, instead of taking just `O(k)` time where `k == len([foot]) == 1` the concatenation of them (`body + [foot]`) will take `O(n + k)` where `n == len(body)`. This would most likely show up if `body` was huge since `foot` probably won't be longer than 1 in most cases.

you can see the memory implications in the following C snippets

from the source of `list_concat`:

```c
    size = Py_SIZE(a) + Py_SIZE(b);
    if (size < 0)
        return PyErr_NoMemory();
    np = (PyListObject *) PyList_New(size);
```

versus this one from `listextend`:

```c
        if (list_resize(self, m + n) == -1) {
            Py_DECREF(b);
            return NULL;
        }
```

this is probably a premature optimization, but it never hurts to know how `list`s work.