Interactive GAE shell

Usage:
```
./run.py --shell
```
or remote shell
```
./run.py --rshell
```
``` python
=== Welcome to gae-init remote shell ====
---------- Please be careful ------------
my-gae-init.appspot.com> from model import User
my-gae-init.appspot.com> User.query().count()
my-gae-init.appspot.com>: 9
my-gae-init.appspot.com> for i, user in enumerate(User.query().fetch()):
                   ....:     print u'%s %s' % (i, user.name)
                   ....:
0 gmist
1 Serg
2 Serg
3 Panayiotis
4 Panayiotis
5 Pasha Gagin
6 Serg
7 Panayiotis
8 Lipis

my-gae-init.appspot.com> User.query().fetch()[5].key.delete()
my-gae-init.appspot.com> User.query().count()
my-gae-init.appspot.com>: 8
my-gae-init.appspot.com> for i, user in enumerate(User.query().fetch()):
                   ....:     print u'%s %s' % (i, user.name)
                   ....:
0 gmist
1 Serg
2 Serg
3 Panayiotis
4 Panayiotis
5 Serg
6 Panayiotis
7 Lipis

```