add support for 'bool' datatype in binary tables

Hi Erin,

I'm having deja vu about this, but this patch allows fitsio to write boolean columns to binary tables.  This test case:

```
import numpy as np
import fitsio
x = np.zeros(10, bool)
x[5:] = True
fitsio.write('test.fits', [x], names=['x'], clobber=True)
```

used to fail like:

```
> python test.py
Removing existing file
Traceback (most recent call last):
  File "test.py", line 7, in <module>
    fitsio.write('test.fits', [x], names=['x'], clobber=True)
  File "/Users/dstn/fitsio/fitsio/fitslib.py", line 227, in write
    compress=compress, header=header, **keys)
  File "/Users/dstn/fitsio/fitsio/fitslib.py", line 460, in write
    table_type=table_type)
  File "/Users/dstn/fitsio/fitsio/fitslib.py", line 663, in write_table
    header=header)
  File "/Users/dstn/fitsio/fitsio/fitslib.py", line 755, in create_table_hdu
    names, formats, dims = collection2tabledef(data, names=names, table_type=table_type)
  File "/Users/dstn/fitsio/fitsio/fitslib.py", line 3023, in collection2tabledef
    _, form, dim = npy2fits(send_dt,table_type=table_type)
  File "/Users/dstn/fitsio/fitsio/fitslib.py", line 3119, in npy2fits
    name, form, dim = npy_num2fits(d, table_type=table_type)
  File "/Users/dstn/fitsio/fitsio/fitslib.py", line 3145, in npy_num2fits
    raise ValueError("unsupported type '%s'" % npy_dtype)
ValueError: unsupported type 'b1'
```

and with this patch it works:

```
> python test.py
Removing existing file
> liststruc test.fits

HDU #1  Array:  NAXIS = 0,  BITPIX = 16

HDU #2  Binary Table:  1 columns x 10 rows
 COL NAME             FORMAT
   1 x                L               

> tablist test.fits

    x 
   1 F 
   2 F 
   3 F 
   4 F 
   5 F 
   6 T 
   7 T 
   8 T 
   9 T 
  10 T 
```

cheers,
--dustin