Polish deployment tests
Ensure DeploymentInfo contextPath is never "/"

Undertow 1.1 expects that DeploymentInfo.contextPath is set to "/" for
a root context. If it is left as "" the session cookie path is not
correctly set. See UNDERTOW-350 for background.

This commit simplifies the original work-around committed in 78c22813d.

Fixes gh-2065
Improve exception message for Weblogic

Ensure that a sensible exception message is thrown if the user happens
to include the logback jar in their deployment.

Fixes gh-2077
Document how-to for Weblogic deployment

Fixes gh-2078
Fix JMS support in the CLI

Partly back port changes from affb202e and 85c95744f to fix the usage
of JMS in the CLI. Restore the integration test using HornetQ and fix the
coordinates of the JMS API.

Fixes gh-2075
Merge branch '1.1.x'
Add undertow websockets dependency
Resolve placeholders in @ConfigurationProperties prefix
Add missing description
Use wesocket dependency from Undertow starter
Don't resolve ConfigurationProperties placeholders

Revert commit 3ad43e0d445d15f03f92f758ced5ee5c64484806 to give us
a little more time to consider how this will impact tooling.
Polish
Polish
Merge branch '1.1.x'
Guard for null BeanFactory in @ConditionalOnBean

See gh-2080
Merge branch '1.1.x'
Cross-reference "Create a deployable war" how-to

Add a tip for both the Maven and Gradle "Packaging executable jar and
war files" section referring to the how-to.

Fixes gh-2086
Set the default session timeout to 30 mins

Update AbstractConfigurableEmbeddedServletContainer to set the default
session timeout to 30 minutes. Also correct Javadoc to specify that
the default is '30 minutes'.

Fixes gh-2084
Merge branch '1.1.x'

Conflicts:
	spring-boot/src/main/java/org/springframework/boot/context/embedded/jetty/JettyEmbeddedServletContainerFactory.java
Ensure Undertow session timeout is set correctly

Assume that Undertow uses -1 for "no expiry".

See gh-2084