INT-3154/INT-3137 JavaDoc Formatting

INT-3154 Use SPR Java7 stylesheet to put a box around `<pre class="code"/>`
code.

Update `<pre/>` tags to include class="code".

INT-3137 Remove NOTICE from `JdbcChannelMessageStore`.

JIRA: https://jira.springsource.org/browse/INT-3137
      https://jira.springsource.org/browse/INT-3154