Revert "Added precheck to check kernel version 4.2 on Ubuntu 14.04."

Upgrade the kernel version is not acceptable for the server in most
of case. I do not see the issue when using ubuntu 14.04 default
kernel with docker aufs storage driver.

Even if there is some wrong in the aufs driver, we could recommend
the user to use other drivers, like lvm, brtfs or even overlay driver.

This reverts commit 833c1269.

Change-Id: I6ee71ecd1ca64777b874bfcc342162622643b89c

ansible/roles/prechecks/tasks/package_checks.yml

@@ -11,12 +11,3 @@
   register: result
   changed_when: false
   failed_when: result.stdout | regex_replace('ansible (\\d+\\.\\d+\\.\\d+)', '\\1') | version_compare(ansible_version_min, '<')
-
-# If this fails run "apt-get install linux-image-generic-lts-wily"
-- name: Checking LTS wily kernel version 4.2 on Ubuntu 14.04
-  command: uname -r
-  register: result
-  changed_when: false
-  failed_when: result.stdout | regex_replace('(\\d+\\.\\d+).*', '\\1') | version_compare(ubuntu_kernel_version_min, '<')
-  when:
-    - ansible_distribution == 'Ubuntu' and ansible_distribution_version == '14.04'

ansible/roles/prechecks/vars/main.yml

 docker_version_min: '1.10.0'
 docker_py_version_min: '1.6.0'
 ansible_version_min: '2.0.0'
-ubuntu_kernel_version_min: '4.2'