Add documentation for email integration

Closes gh-1904
Fix typo
Document init CLI command

Closes gh-1799
Add missing properties metadata

Fixes gh-1829
Upgrade to HikariCP 2.2.5

Closes gh-1897
Restore compatibility with Jetty 8 when SSL is being used

ServerConnector is in different packages in Jetty 8 and Jetty 9 which
was leading to a NoClassDefFounderError when SSL was used with
Jetty 8.

This commit updates SslServerConnectorFactory to return an
AbstractConnector, a super class of ServerConnector, that is in the
same package in both Jetty 8 and Jetty 9. This class does not provide
a setPort method so the setting of the port has been pushed down into
the SslServerConnectorFactory implementation.

SSL samples for both Jetty 8 and Jetty 9 have been added to verify
SSL with both supported versions of Jetty.

Closes gh-1925
Polish
Add 'module' repacker layout

Add a 'module' layout for the repackager which includes all 'compile'
and 'runtime' scope dependencies and does not require a main class.

Fixes gh-1941
Allow servlet context parmeters to be configured via declaratively

Previously, configuration of a ServletContext init parameter required
the use of a ServletContextInitializer bean. This commmit adds
support for declarative configuration via the environment using
server.context_parameters.<name>=<value>.

Closes gh-1791
Use embedded docbook XSLT files

Switch from external docbook XSLT to those shipped as part of the
Maven plugin.

Fixes gh-1942
Merge branch '1.1.x'
Find @ConfigurationProperties annotation on proxy

Update ConfigurationPropertiesReportEndpoint to find
@ConfigurationProperties using `context.findAnnotationOnBean` rather
than `AnnotationUtils.findAnnotation`. This will correctly find the
annotation even if the bean is an interface based proxy.

Fixes gh-1927
Merge branch '1.1.x'
Don't flush in ErrorPageFilter for < 400 response that's committed

Previously, for a non-async response with a successful status (< 400),
ErrorPageFilter would always call flushBuffer. This triggers an
exception in Tomcat if the client has closed the connection before the
response has been fully sent. In this case, Tomcat treats the response
as successful and commits it before control returns to the filter.

This commit updates ErrorPageFilter to only perform the flush if the
response has not already been committed, leaving any further flushing
that may be necessary to be handled by the servlet container.

Fixes gh-1938
Merge branch '1.1.x'
Omit null pathInfo from ErrorPageFilter's error message

Fixes gh-1944
Merge branch '1.1.x'
Upgrade to Spring Integration 4.0.5.RELEASE

Closes gh-1905
Upgrade to Spring AMQP 1.3.7.RELEASE

Closes gh-1906
Upgrade to Tomcat 7.0.57

Closes gh-1936