Maven support

I have added a pom.xml and configured it so that it can be released to https://oss.sonatype.org, this way it is possible to easy use subtitleConverter library in Maven Java projects
I had to move source files to src/main/java folder, there are no changes to them

released jars are on:
https://oss.sonatype.org/content/groups/public/com/github/riccardove/easyjasub/subtitleConvert/1.0.2/