Do final alignment based on presence of <,>,^,0= in format string

Beginning to finalize the table-column alignment options for pprint in Table package.
@agroener - I was very confused why travis is failing the tests, but it seems that the `lambda` definition does not do the look-up in `justify_functions` directly, but only later, when it is executed. I can get all tests to pass when I split this line into two:
```
                    justify_function = justify_functions[col.format[1]]
                    justify = lambda str, col_width: justify_function(str, col_width, col.format[0])
```