Remove redundant shebangs

Remove redundant shebangs from files that are not used as scripts.

https://fedorahosted.org/freeipa/ticket/3853
Show human-readable error name in error dialog title

Fixes RPC server's JSON encoding of exception's name.

It allows to show the name in Web UI's error dialog title.
Perform dirsrv tuning at platform level

When configuring the 389 Directory Server instance, we tune it
so that number of file descriptors available to the DS is increased
from the default 1024 to 8192.

There are platform specific steps that need to be conducted
differently on systemd compatible platforms and sysV compatible
platforms.

systemd: set LimitNOFILE to 8192 in /etc/sysconfig/dirsrv.systemd
sysV: set ulimit -n 8192 in /etc/sysconfig/dirsrv
      set ulimit - nofile 8192 in /etc/security/limits.conf

https://fedorahosted.org/freeipa/ticket/3823
Make CS.cfg edits with CA instance stopped

This patch makes sure that all edits to CS.cfg configuration file
are performed while pki-tomcatd service is stopped.

Introduces a new contextmanager stopped_service for handling
a general problem of performing a task that needs certain service
being stopped.

https://fedorahosted.org/freeipa/ticket/3804
Add integration tests for Kerberos Flags

Add integration tests for the Kerberos Flags feature:
http://www.freeipa.org/page/V3/Kerberos_Flags#Test_Plan
(except the web UI tests).

https://fedorahosted.org/freeipa/ticket/3831