Description of problem:
As per https://github.com/freeipa/freeipa/pull/556/ IPA doesn't allow
standalone KRA uninstallation. We should update warning message presented when
IPA KRA installation fails with some error.

# ipa-kra-install
Directory Manager password:


===================================================================
This program will setup Dogtag KRA for the IPA Server.


Configuring KRA server (pki-tomcatd). Estimated time: 2 minutes
  [1/9]: creating installation admin user
  [error] ACIError: Insufficient access: SASL(-1): generic failure: GSSAPI
Error: Unspecified GSS failure.  Minor code may provide more information
(Decrypt integrity check failed)

Your system may be partly configured.
Run ipa-kra-install --uninstall to clean up.

Insufficient access: SASL(-1): generic failure: GSSAPI Error: Unspecified GSS
failure.  Minor code may provide more information (Decrypt integrity check
failed)
The ipa-kra-install command failed. See /var/log/ipaserver-kra-install.log for
more information

Version-Release number of selected component (if applicable):
# rpm -q freeipa-server freeipa-client ipa-server ipa-client 389-ds-base pki-ca
krb5-server
package freeipa-server is not installed
package freeipa-client is not installed
ipa-server-4.5.0-7.el7.x86_64
ipa-client-4.5.0-7.el7.x86_64
389-ds-base-1.3.6.1-9.el7.x86_64
pki-ca-10.4.1-2.el7.noarch
krb5-server-1.15.1-7.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Install IPA KRA without kinit

Actual results:
User is presented with 'Run ipa-kra-install --uninstall to clean up.'

Expected results:
Above error should be rephrased as standalone KRA uninstall is not supported.
Also, man page should be updated.