Modified PageController class to use the new Logging Abstractions. 	Now, logging through the api is handled through ChoiceLogManager. 	However, we make assumptions that we can use the aggregate requests api function in every situation 	Error handling may need to be added for logging (especially for api calls). 	New changePage method added which will take care of flushing logs and marking time spent on page before changing page for each button click. 	Moved logUserActions functionality to ChoiceLogManager.
Modified PageController class to use the new Logging Abstractions.
	Now, logging through the api is handled through ChoiceLogManager.
	However, we make assumptions that we can use the aggregate requests api function in every situation
	Error handling may need to be added for logging (especially for api calls).
	New changePage method added which will take care of flushing logs and marking time spent on page before changing page for each button click.
	Moved logUserActions functionality to ChoiceLogManager.

Some notes on the design of the Logging Abstraction:
	I considered using a more specific LabNotebook logging abstraction,
	but in the end decided on a more general (user builds string which goes into log. log can then be flushed to notebook) approach.
	I don't know which way would be better, but I think this way is a little bit more flexible. The PageController class (which will eventually be changed)
	still needs to know how to build the Lab Notebook log string. If there is a better way, we should consider it.

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