deploy: Use synnefo user and group

In short make Archipelago, gunicorn and snf-dispatcher run as
synnefo:synnefo.

Since we are using NFS we create synnefo group with common
gid across all nodes. The Archipelago dir to be exported
will be owned by root:synnefo and have group write permissions.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: A workaround for Archipelago bug

Due to a bug in Archipelago [2] we chown /dev/shm/posixfd after
Archipelago restart.

This should be reverted after this PR is merged and a
new Archipelago version is released.

[2] https://github.com/grnet/archipelago/pull/44

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
docs: Update centos install guide wrt synnefo user

Additionally change the NFS dirs to /srv/pithos/{blocks,maps,locks}.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
docs: Update debian install guide wrt synnefo user

In short Synnefo will run as synnefo:www-data while Archipelago as
synnefo:synnefo. The exported directories in NFS should be
root:synnefo with g+ws.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
docs: Update upgrade notes wrt synnefo user

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
docs: Update admin guide wrt synnefo user

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
webproject: Change user in gunicorn example file

..shipped under /etc/gunicorn.d/synnefo.example.

Let gunicorn run as synnefo:synnefo

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>