Moved installation of prerequisite software

Prerequisite software installation has been moved before the user
prompts, to allow immediate usage of certain features of the software.
Removed ntp installation from playbook

Installation of ntp is now handled in the bootstrap.sh folder and is no
longer needed in the playbook.
Modified statement to echo to both log file and

standard out. This ensures that the message can be seen in both places.
Also changed to a multiline if statement instead of a one line
statement.
Added user input for ntp server

Bootstrap.sh will now ask the user for the appropriate time server they
wish to use to synchronize their machine with.
Added sntp prerequisite

Installing sntp will allow one off time sync necessary to prepare to
machine.
Added a timeout for sntp command

Modified the timeout from the default 68 seconds to a more reasonable 3
seconds to prevent the user from waiting too long.
Added time server to group_vars

Timeserver has been added to group vars to allow it to be accessible to
the ansible playbook. This value will be used in later configuring the
ntp server.
Added task to overwrite ntp.conf file

New task has been added to use a template file to overwrite the existing
ntp.conf file.
Template ntp.conf file added

The template ntp.conf file makes use of the ntp server value stored in
group_vars and will replace the existing ntp.conf file which uses
default centos pool servers.
Changed back to ntpdate

ntpdate is more functional and more reliable than sntp, which is why the
switch was made.
Merge pull request #87 from ausaccessfed/feature/ntp-presync

Feature/ntp presync
Resolves #77