[enhancement] resolves #7 - Configure pom.xml to generate reports.

I want to resolve #7 in this commit that maven report settings was configured.

Added configurations for reporting plugins below:
- maven-jxr-plugin
- maven-javadoc-plugin
- javancss-maven-plugin
- jdepend-maven-plugin
- taglist-maven-plugin
- maven-checkstyle-plugin
- maven-pmd-plugin
- findbugs-maven-plugin
- maven-surefire-report-plugin
- jacoco-maven-plugin
- maven-changelog-plugin
- maven-changes-plugin

'maven-changelog-plugin' and 'maven-changes-plugin' will be effective when the application is built for release.
The reason, that configurations are separated for usual build and release build, is that maven-changes-plugin requests to Github via API which limits a number of requests per hour.
Refer to the URL below, if you need more details.
https://developer.github.com/v3/rate_limit/

To make sure these settings, you wolud execute a command 'mvn clean site', and put '-Prelease' parameter of the command when you generate the reports for release.
Then maven site htmls are generated into /target/site directory of each project.
You open 'index.html' and see a contents table on the left.
Click report menu link, you will see the reports. Try it, please.