Add a Introduction Certificate Extension
Merge branch 'refactoring' into web-of-trust
Add Test case for Web-of-Trust, add get/set methods in certificate-extension classes
Merge branch 'refactoring' into web-of-trust
Introduction certificate extension is working now
Merge branch 'refactoring' into web-of-trust
Add basic web of trust policy manager
Merge branch 'refactoring' into web-of-trust
Merge branch 'refactoring' into web-of-trust
Add IntroCertificate Class
Merge branch 'refactoring' into web-of-trust
Add implementation of IntroductionCertificate
Add BasicWOTPolicyManager
Merge branch 'refactoring' into web-of-trust
Add getPublicKeyName method in Certificate
Revert "Add getPublicKeyName method in Certificate"

This reverts commit 68c180ea439a249b84b1ea49998603412d92450b.
Revert "Revert "Add getPublicKeyName method in Certificate""

This reverts commit 10223732f58cab757876700add2e3515b6c54d1d.
Make verifySignature as a static method of PolicyManager
Add techinical document