DATAREDIS-419 - Move project build to Maven.

- Introduce Maven pom.xml.
- Moved Asciidoctor files to src/main/asciidoc.
- Moved notice.txt etc. to src/main/resources.
- Add logback.xml
- Update Makefile to use maven and pick build profiles.
- Update template.mf to pick up versions in pom.xml
- Add build matrix for spring versions to .travis.yml
- Use container based travis infrastructure.
- Update readme.

Original pull request: #167.

Makefile

@@ -12,7 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-REDIS_VERSION:=3.0.2
+REDIS_VERSION:=3.0.7
+SPRING_PROFILE?=ci
 
 #######
 # Redis
@@ -95,5 +96,5 @@ stop: redis-stop sentinel-stop
 test:
 	$(MAKE) start
 	sleep 2
-	-$(PWD)/gradlew clean build -DrunLongTests=true -S
+	mvn clean install -DrunLongTests=true -P$(SPRING_PROFILE)
 	$(MAKE) stop