New test decay files

[eduardo-rodrigues]

Adding a handful of .dec decay files for testing purposes.

@henryiii, what's your take on the location of such files? They are under decaylanguage/data but we could as well have then under a new directory tests/data.

[coveralls]

Coverage remained the same at 0.0% when pulling 0ebfbb3 on eduardo-testdata into 26d7ead on master.

[coveralls]

Coverage remained the same at 0.0% when pulling d8c9bb9 on eduardo-testdata into 26d7ead on master.

[henryiii]

Testing files should be in tests, since you don't want to distribute them in the package. If something might be of general use (a full file like the LHCb one), that can be in the package in data.

[eduardo-rodrigues]

That's my opinion too. All test files moved to new directory tests/data.