Remove mentionings of guava (#303)

* Remove the guava dependency from README.md

Signed-off-by: Sven Strickroth <email@cs-ware.de>

* Remove guava also from the documentation

Signed-off-by: Sven Strickroth <email@cs-ware.de>

* Update RELEASE-checklist.sh to not contain guava any more

Signed-off-by: Sven Strickroth <email@cs-ware.de>

---------

Signed-off-by: Sven Strickroth <email@cs-ware.de>

README.md

@@ -7,7 +7,7 @@ A fast and easy to configure HTML Sanitizer written in Java which lets
 you include HTML authored by third-parties in your web application while
 protecting against XSS.
 
-The existing dependencies are on guava and JSR 305.  The other jars
+The existing dependency is on JSR 305. The other jars
 are only needed by the test suite.  The JSR 305 dependency is a
 compile-only dependency, only needed for annotations.
 

RELEASE-checklist.sh

@@ -8,7 +8,6 @@ set -e
 
 
 # Make sure the build is ok via
-mvn -Dguava.version=27.0-jre -f aggregate clean verify                    javadoc:jar source:jar
 mvn                          -f aggregate clean verify jacoco:report site javadoc:jar source:jar
 mvn install
 mvn org.sonatype.ossindex.maven:ossindex-maven-plugin:audit -f aggregate

docs/getting_started.md

@@ -4,12 +4,11 @@
 
 If you are using Maven then follow the [maven](maven.md) directions to
 add a dependency.  Otherwise,
-[download prebuilt jars](https://search.maven.org/#artifactdetails%7Ccom.googlecode.owasp-java-html-sanitizer%7Cowasp-java-html-sanitizer%7C20180219.1%7Cjar)
+[download prebuilt jars](https://search.maven.org/artifact/com.googlecode.owasp-java-html-sanitizer/owasp-java-html-sanitizer/)
 or `git clone git@github.com:OWASP/java-html-sanitizer.git` and build
 the latest source.
 
-Unless maven is managing your CLASSPATH for you, you need to add both `owasp-java-html-sanitizer.jar` and the
-Guava JAR.
+Unless maven is managing your CLASSPATH for you, you need to add `owasp-java-html-sanitizer.jar`.
 
 Once you have your CLASSPATH set up correctly with the relevant JARs
 you should be able to add