Update WorkspaceFactory to use the MemoryManager

[Nick Draper]

Currently the Workspace Manager uses the requested size of a workspace to decide wether to create a ManagedWorkspace or not. This is done by comparing HistogramCount*TimeBins to a value in the .properties file.

This should be updated to use the information that can be provided by the MemoryManager. I suggest that we change it so it reads a value from the .properties file that gives a percentage of the available memory that may be used for the workspace. Therefore if they have the value set to 50% then if a full workspace would take less than 50% of the available memory then that would be returned, otherwise a managed workspace would be used.

You will need to do a bit of benchmarking to investigate what a sensible default value should be.

[Roman Tolchenov]

(In [1316]) WorkspaceFactory uses memory information to decide when to create a ManagedWorkspace. re #206

[Stuart Campbell]

This ticket has been transferred to github issue ​1054