When built in 'group' mode, the write permissions of all created files will
be activated for a certain group of users in the host operating system. The
user specifies the name of the group with the '--group' option at configure
time. At the very start, the './project' script checks to see if the given
group name actually exists or not (to avoid hard-to-debug errors popping up
later).

Until now, the checking 'sg' command (that was used to build the project
with group-writable permissions) would always fail due to the excessive
number of redirections. Therefore, it would always print the error message
and abort.

With this commit, the output of 'sg' is no longer re-directed (which also
helps users in debuggin). If the group does actually exist, it will just
print a small statement saying so, and if it fails, the error message is
printed. This fixed the problem, allowing maneage to be built in
group-mode.

I also noticed that the variable name keeping the group name
('reproducible_paper_group_name') used the old name for the project (which
was "Reproducible paper template"! So it has been changed/corrected to
'maneage_group_name'.