Update __main__.py

[algchyhao]

delete "." in line 3
from .swmmio import Model -> from swmmio import Model
resolve the error: "from swmmio.swmmio import Model, no module named swmmio" balabala......

Closes #61

[aerispaha]

@algchyhao thanks for this fix!

Note that I've also updated the dependecies in requirements.txt and setup.py to explicitly set the version number for each dependency of swmmio. Because these weren't previously set explicitly, we were running into compatibility issues with the Windows Python 2.7 builds (which is why some of tests on this PR failed at first).

All of this will be included in the next swmmio release. For now, I recommend pulling down these updates in from the master branch v0.3.6.dev0

[aerispaha]

👍