new checks related to file size, presence and congruence

[mobb]

per chat with Mark and Duane, 2 new checks

1. for entity size presence: [entity]/physical/size
   entitySizePresence - statusType = warn

2. congruence of stated value with size found when pasta downloads the entity
   entitySizeCongruence - statusType = error

these are entered in the google spreadsheet sticky rows 96, 97

since one of them has statusType error, we will convene meeting of the ECC working group to discuss and schedule.

[mobb]

Examining the entity size is a method for checking that this is the correct entity. So in that sense, these will operate like the 2 integrityChecksum checks, but will not control pasta behavior

[mobb]

related to #10

[srearl]

Love the checks but not so sure that this issue is all that much related to #10.

[mobb]

it was an entity duplication problem that prompted the suggestion of this check. however in an of itself, checking file size does nothing to control duplication, although it might help identify entity1 as the same as entity2.