Polish spring-boot-starter-data-gemfire's pom
Replace column name using reserved keyword

This commit replaces the "index" property of Review to use a custom
column name ("idx") as index is a reserved keyword in some RDMS such
as Oracle and MySQL.

Fixes gh-752
Upgrade to Reactor 1.1

Fixes gh-706
Add support for HikariDataSource

We still prefer Tomcat if it is available (that can change
if the community asks loudly enough). Hikari is supported
via the same spring.datasource.* properties as Tomcat (and
DBCP), with some modifications:

* The validation and timeout settings are not as fine-grained
in Hikari, so many of them will simply be ignored. The most
common options (url, username, password, driverClassName) all
work as expected.

* The Hikari team recommends using a vendor-specific DataSource
via spring.datasource.dataSourceClassName and supplying it with
Properties (spring.datasource.hikari.*).

Hikari prefers the JDBC4 isValid() API (encapsulates vendor-
specific queries) which is probably a good thing, but we
haven't provided any explicit support or testing for that yet.

Fixes gh-418
Convert actuator-ui sample to FreeMarker

See gh-679
Make `loader` Windows compatible

The encoding of UTF-8 (et al.) chars in the
JarUrlConnection has to be made explicit, otherwise
Wdinows apparently does not pick the default(?).

Fixes gh-711, Fixes gh-753
Minor improvement in simple sample test
Add more runtime metrics like information about heap, class loading and threads to the metrics infrastructure
Add URLs from parent classloader in executable jar

$ (cd spring-boot-tools; mvn clean install -DskipTests=true)
$ (cd spring-boot-samples/spring-boot-sample-simple/; mvn clean package)
$ java -jar spring-boot-samples/spring-boot-sample-simple/target/spring-boot-sample-simple-1.1.0.BUILD-SNAPSHOT.jar

(vanilla executable jar archive: works)

$ java -cp spring-boot-samples/spring-boot-sample-simple/target/spring-boot-sample-simple-1.1.0.BUILD-SNAPSHOT.jar:spring-boot-tools/spring-boot-loader/src/test/resources/jars/app.jar org.springframework.boot.loader.JarLauncher

(jar archive plus vanilla plugin: works)

$ (cd spring-boot-samples/spring-boot-sample-simple/target; rm -rf app && mkdir $_ && cd $_ && jar -xf ../*.jar)
$ java -cp spring-boot-samples/spring-boot-sample-simple/target/app/ org.springframework.boot.loader.JarLauncher

(exploded directory: works)

$ java -cp spring-boot-tools/spring-boot-loader/s:spring-boot-tools/spring-boot-loader/src/test/resources/jars/app.jar org.springframework.boot.loader.JarLauncher

(exploded directory with plugin jar: works)

Potential fix for gh-529
Fix build

Two modules are still relying on the spring-boot test-jar but it was
not generated anymore. Adding the generation of test-jar again as
a workaround until we completely removes the use of it.
Upgrade to Spring Integration 4.0