Add volume and fileCount to Investigation and Dataset

[antolinos]

It has always been a sort of issue to get the calculation with the total volume of a number of files. We have solved it by storing these values as DataParameter and InvestigationParameters and they are recalculated any time a file, dataset or investigation is modified in ICAT

We can live without but it might be interesting to consider to add them as fields of the tables Investigation and Dataset.

Example:

Field	Type	Description
name	String [255] NOT NULL	A short name for the investigation
startDate	Date
doi	String [255]	The Digital Object Identifier associated with this investigation
summary	String [4000]	Summary or abstract
modId	String
releaseDate	Date	When the data will be made freely available
visitId	String [255] NOT NULL	Identifier for the visit to which this investigation is related
createId	String
createTime	Date
modTime	Date
endDate	Date
title	String [255] NOT NULL	Full title of the investigation
volume	Integer	Total volume of the investigation
fileCount	Integer	Total number of files of the investigation

[RKrahl]

Note that this partly duplicates #233 which adds Dataset.datasetSize and Investigation.investigationSize but no fileCount.

[RKrahl]

@antolinos, would you agree to name that new attribute Dataset.datasetSize and Investigation.investigationSize respectively instead of volume as done in #233?

[antolinos]

@antolinos, would you agree to name that new attribute Dataset.datasetSize and Investigation.investigationSize respectively instead of volume as done in #233?

Perfectly fine with me!!