Prep v6.2.11

[belgattitude]

Added

• Build: Support for Gradle (still relying on ant build.xml), see #5 and #9
• Build: New tasks added in gradle 'jacocoTestReport', see P/R #9
• Test: Resurrect existing unit tests
• Test: test and coverage using Jacoco added, see P/R #9
• Doc: trick to build when default interpreter is php 7+, see #4
• License: MIT license where applicable, see #10

Removed

• Removed obsolete javax.script sources

Changed

• Moved namespace php.java into io.soluble.pjb, see P/R #9
• Project directory structure mavenized, sources moved from './server' to './src/main/java', see P/R #9