let generate method to create DummyApartment object

The generate method return a DummyApartment instance.
It has methods #[] and #[]= that accept String or Symbol key.
Also has the methods #address, #address=, #geo, #geo= and so on.
DummyApartment delegates methods to Hash class. so, for example,
DummyApartment.generate.keys will work although DummyApartment doesn't
have method #keys.
Merge branch 'accessor'
fix bug of gen_address

It have generated street number like '40123'.
The street number started with non-zero number and the rest part is
serial numbers whose length is random.
This commit fix it. Now generates street number more like real.
bump version to 0.0.2