New updates to context-match

[HardiRathod]

New features added

• custom context file
• string separations
• discounting property values for missing properties in q_nodes.

[saggu]

@HardiRathod your unit tests should be more extensive. Rather than checking for non zero values, you should check for exact values. Unit tests should have a test for each of date, string, quantity etc and then a combination of these, type of context matches. The tests should check for exact scores. Please add more precise testing