Unnecessary calculations for mean DAP over time plot

[David Platten]

When this plot is selected views.py calculates the mean DAP and frequency for each protocol in the data: this is not required for this plot type. This will slow up the calculation time when only this plot type is required.

[David Platten]

Amended views.py to stop unnecessary calculation of mean DAP and frequency of each protocol when mean DAP over time plot selected on its own. Fixes issue #240.

→ <<cset 462e38814708>>