Introduce omero.constants.DEFAULTBLOCKSIZE

Use of MESSAGESIZEMAX (64MB in kb) was seriously affecting
performance on upload of FS files. This commit introduces
DEFAULTBLOCKSIZE at 5MB in byte.

A further option would be to make it configurable via etc/ice.config.
Fix whitespace in client.{h,cpp}
Make client-side block-size configurable

DEFAULTBLOCKSIZE is now properly just the client-side default.
Setting omero.block_size on the omero.client object can modify
the value that client.getDefaultBlockSize() will return. Tests
added in each of the languages.
Improve the file upload logging slightly.
Merge pull request #840 from joshmoore/fs-block-size

Introduce omero.constants.DEFAULTBLOCKSIZE