Travis and gtest

I tweaked **CMakeLists** to allow to find **GTest** with the environment variable GTEST_ROOT. If it not find these variable, then will try to find it with find_package (find_package not always sworks well with GTest).

Also, have the initial version of **.travis.yml** with some commented lines that probably will need to uncomment  in a future when we begin to use third party libs.

I added a initial version of **.editorconfig** to "enforce" 4 spaces indent and unix file ending (your IDE/text editor should have the editor config plugin for this)