Configure buildpack support JAR in Tomcat

Download the JAR from its repository. Add the JAR to Tomcat's lib
directory and define a listener in server.xml.

The current version of the support JAR provides a listener which
shuts down Tomcat if the web application fails to start. This
improves the diagnostics when pushing such an application to Cloud
Foundry as Cloud Foundry checks the health of Tomcat rather than of
the application.

[#49091441]
Merge 49091441-kill-tomcat-if-application-fails-to-start to master

[#49091441]
Fix messages about support JAR

[#49091441]
Merge 49091441- to master

[#49091441]
Fix support JAR filename in lib directory

Also add the support JAR to git.

[#49091441]
Merge 49091441- to master

[#49091441]
Link README to buildpack support git repository

[#49091441]
Merge 49091441- to master

[#49091441]
Upgrade buildpack support JAR

Version 1.1.0 halts Tomcat rather than throwing an exception.
[#49091441]
Merge 49091441- to master

[#49091441]
Remove system.properties

Previously, the buildpack could be configured by adding a
system.properties file into an application before it was pushed.  This
conflated the actions of pushing and application and configuring the
environment that the application ran in.  This change removes most of
the use of system.properties from the system, but does not quite
remove it all.  The JRE memory subsystem still has references to
system.properties (although those code-paths will never be called) and
those will be removed in another story.

In addition to the code changes around system.properties, the
structure of the documentation has been changed.  The documentation is
now in multiple Markdown files located in the docs/ directory.  These
files are linked to from a table of contents embedded in README.md.
This means that a user will see the documentation links on first
arrival at the buildpack and will be sent to more detailed information
that is versioned with the buildpack code itself.

[#52105249]
Merge 52105249-remove-system-properties to master

[Completes #52105249]
Kill JVM on OOM

[#51561265]
Merge 51561265-halt-JVM-on-OOM to master

[#51561265]
Remove system.properties support

Previously the memory subsystem relied on system.properties support.
Now that it has been removed, this area must change.  This change
restructures the code slightly, and removes the need to declare
mappings for both types of JRES.  It also ensures that knowledge of
valid configuration parameters is handled via polymorphism.

[#52129161]
Merge 52129161-remove-system-properties to master

[Completes #52129161]
Clarify detection criteria and tags

[#52140727]
Merge 52140727- to master

[#52140727]
Improve formatting

[#52140727]
Improve formatting

[#52140727]