[FLINK-2359] [java api] Add factory methods to the Java TupleX types

[ggevay]

I added the creation of the factory method to the TupleGenerator.

I also fixed some inconsistencies between the generator and generated files: it seems that some modifications were made to generated files without modifying the generator. I incorporated these changes to the generator (see the first three hunks in the generator) (except for some whitespace changes in the first three modified files).

I randomly changed some constructor calls into using the new method for testing and demonstration purposes (see the last two changed files).

[aljoscha]

Should we call it of instead of create? In other parts, such as the windowing helpers we also have of for these shortcut constructors.

[mbalassi]

I also prefer of as a method name.

[mxm]

Thanks for adding the generator methods. That's definitely more convenient than using new. I also prefer of instead of create.

[ggevay]

Ok, of looks better indeed. I will modify it.

[fhueske]

PR looks good to me except for the purely reformatting changes which should be excluded from the PR.
After that it's good to merge, IMO.
Thanks!

[ggevay]

@fhueske:
I included the reformatting changes because the generator is making them. This is happening because some modifications were made directly to some generated codes in the past, which made them inconsistent with the generator. But I guess the goal should be that the generator program would have no effect on the master. One way to achieve this is to commit the changes the generator makes, and the other way would be to change the generator to follow the reformatting. Do you think that I should change the PR to the latter with respect to the reformattings as well? (I already did the latter with respect to some real changes, see my opening comment.)

[fhueske]

Ah OK. It's fine to commit the changes if they are caused by the TupleGenerator.
I don't think it's necessary to adapt the generator to avoid the changes.

[fhueske]

I'm going to merge this PR