new store functionality and partial PEP8 conformity 

**store** functionality
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I have added the **-s/--store** option that allows users to store the answers in a **howdoi.txt** in their current working directory. 

**PEP8 conformity**
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I have tried to eliminate trailing whitespaces and long lines where it seemed reasonable. I used the **pep8** cli to parse the python files.

**TODO:**

* With the colored output option set, the content stored on file is polluted with some of the formatting characters. Correcting this, not done yet.
* Adding a test case for the store functionality not done yet.