suprsync: Change default chmod to set world-readable

[BrianJKoopman]

Description

This PR changes the default --chmod argument passed to rsync within the suprsync agent to 'g+rwX,o+rX', which ensures files are group writable and world readable.

Motivation and Context

Resolves #871.

How Has This Been Tested?

I tested setting this argument via the SCF on the LAT SMuRF servers. It resulted in changing the top level directory permissions from drwxrwx--- to drwxrwxr-x, which is what we want.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.