Moving keystore definition into settings

Adding LDAP StartTLS support ...

Some LDAP server do not allow authenticate with unencrypted password.
This patch is adding the StartTLS support which takes care of the
encryption.

In order to enable the StartTLS, go to "System Settings" and select the
"Enable StartTLS" in the Authentication section. Then make sure that you
add your LDAP certificate into the Java keystore:

$ keytool -import \
          -file /etc/pki/tls/certs/cacert.pem \
          -alias myName \
          -keystore /var/lib/gitbucket/keystore

You can list all keys from the keystore like this:

$ keytool -list -keystore /var/lib/gitbucket/keystore

Fixing command line options in init.d script ...

Adding missing "--host" option and fixing the declaration of other
command line options.

Allow to force HTTPS scheme ...

If the standalone GitBucket instance runs behind HTTPS proxy, the
repository URL always shows HTTP scheme dispute the fact that the
connection is HTTPS. This patch is adding a command line option which
allows to force the HTTPS scheme.

System support for RedHat ...

This commit is adding init.d script and sysconfig file which allows to
run GitBucket in the standalone mode. It also adds the spec file which
allows to build RPM package.