Added a button for "Create node" on clicking which the app enters the create node state.
Updated Readme with the Create Node feature, corrected typos
Minor css changes.
Solved #10, "Adding/Not-Adding Nodes" Status is now indicated by both change in text and color of the  Create node button
Cleaned up urls.py and views.py and checked for pep8 compliance
Added basic edge adding feature and associated states for adding edge mode, etc.
Updated README, with information about the adding edge feature and also describing updates to add nodes feature.
In "Adding Edge" mode, clicking on a blank space should set source_node_id = null to avoid edge creation bug.
Automatic unselection of target node after edge creation, delete button can be used for deleting nodes, edges.
Increased the size of nodes created slightly and solved some edge creation bugs.
Merge branch 'master' of https://github.com/pramttl/pgmpy_viz