Added a builder method to sign/encrypt as a text document

[bjansen]

#60

[bjansen]

I'm not sure how to modify the builder without causing compilation errors in existing projects that are not interested in this new feature. I added a method to Build, but this means it could theoretically be called multiple times:

BouncyGPG
	.encryptToStream()
	.withConfig(...)
	.withStrongAlgorithms()
	.toRecipients(...)
	.andSignWith(...)
	.binaryOutput()
	.textMode()
	.textMode()
	.textMode()
	.textMode()
	.andWriteTo(...)

Also, I haven't added any unit tests yet.

[bjansen]

@neuhalje were you able to take a look at this PR by any chance?

[neuhalje]

Sorry, I completely missed that one!

To remove the "multiple calls possible " topic: Add a new interface that derives from Build and returns Build. Return that from the previous step.

The example projects are a good way to test building: just update their grade/Pom and run the shell script.

Could you also add some unit test?

My next weekends are already planned - I can do an in depth review in two weeks

[bjansen]

Thanks for the suggestions! I added a unit test which checks that encrypted data can be decrypted, but I'm not sure how to check the data is actually encoded as text literal packets. I guess I could use BouncyCastle directly, but I'm not proficient enough with this library.

[bjansen]

@neuhalje do you think you'll have some time in the near future to review this PR? Thanks