Improve MVT tests

[Algunenano]

Currently regress/mvt.sql tests are using the following format:

select 'PG4', ST_AsText(ST_Normalize(ST_AsMVTGeom(
	ST_GeomFromText('POLYGON ((0 0, 10 0, 10 5, 0 -5, 0 0))'),
	ST_MakeBox2D(ST_Point(0, 0), ST_Point(4096, 4096)),
	4096, 0, false)));

Using ST_Normalize here changes the output so it doesn't comply with the MVT spec and also hides any possible error in the polygon rings winding order, like the one solved in ​https://trac.osgeo.org/postgis/ticket/4079

[Raul Marin]

In 16615:

Travis: Install all required dependencies for MVT tests

References #4106

[Raul Marin]

In 16616:

MVT tests: Remove ST_Normalize calls

References #4106

[Raul Marin]

In 16617:

Travis: Install all required dependencies for MVT tests

Closes #4106