Modified svelLex.py to tokenize input file

Used to only tokenize user input; can now tokenize input file with call:
```python svelLex.py <path_to_input_file>```
Fixed shift/reduce conflict and added file parsing

Like svelLex, can now parse input file with call:
```python svelYacc.py <path_to_input_file>
Merge pull request #31 from kaitlinhuben/master

Modified svelLex.py and svelYacc.py to parse input file