Add contrib importance pie chart

[christinaexyou]

This PR is part 2 of addressing issue #114 by making the following changes:

1. Creates a pie chart depicting contributor importance
2. Updates queries/contributors_query.py to query for contributor alias emails and returns the dataframe with an email column included
3. Updates chaoss/chaoss.py

[christinaexyou]

Changes made:

1. Addressed no data issue for PR Review and Issue Open
2. Search for potential bots in login rather than email - this is mostly just a temp fix until we can figure out how to detect bot tags that GH assigns
3. Revert contributors_query.py to the most recent update in the dev branch

[cdolfi]

@christinaexyou is this meant to be closed?

[christinaexyou]

The following changes were made:

1. Corrected original comment about isin for removing bots - it looks for exact matches between the login and the elements in patterns NOT substring matches
2. Updated graph info with a note about contributors that are ID'ed as None

[christinaexyou]

Changes made:

1. Replaced 'contributions' with 'commits' in graph info
2. Added an if statement in Line 210 to make sure the graph still renders if the user chooses NOT to filter out bots
3. Replaced isin with str.contains to filter out rows where Login column value has a substring match for 'bot'

[christinaexyou]

@cdolfi @JamesKunstle Changes made:

1. Added functionality user to create new keywords to filter out contributors by
2. Create dynamically changing title
3. Updated Graph Info description
4. Edited Pandas logic