Use `composer install` rather than `composer update` for installation
Added instructions on how to run phpunit
Adding some basic contribution guidelines
ignore phpstorm project files
Simplify install instructions and use semver operator
Merge pull request #2 from relaxnow/patch-1

Simplify install instructions and use semver operator
Merge pull request #1 from SURFnet/improvement/docs

Minor README(-dev) updates
[#78632442] Ported key loading from various configurations
[#78632442] Missed the utility class in previous commit
[#78632442] Throwing exceptions with a proper message
[#78632442] Adding Additional Exception (testing pivotal hook)
[#78632442] Fixing PSR according to project settings
[#78632442] Fix for not throwing expected exception
[#78627856] Introducing basic configuration
[fixes #78632442] changing api to use interface
Minor CS change to fix build
Show why the build fails in travis rather than only that it fails
show errors of phpcs, optimize phplint
Merge pull request #4 from SURFnet/improvement/display-build-errors-in-travis

Display build errors in Travis
Merge branch 'develop' into feature/signature-validation