Added a configuration file for Travis CI

This configuration script tell travis to install dependent libraries, build program and execute make check command.
Merge pull request #52 from mohammedari/travis-ci

Proposal of automated testing with Travis CI
Changed version to v0.2 in READMEs
Add a travis-ci icon to README files
Merge pull request #54 from Nyoho/travis-ci-icon

Add a travis-ci icon in README.md
Add files of libsoil.
Merge libsoil.
Merge branch 'merge_soil'