Build with Spark 2.3.1, drop Scala 2.10 support, update sbt and sbt-spark-package version

[auroredea]

Hello, We (with @nekonyuu ) changed :

• the version of SBT
• the version of the plugin sbt-spark-package removed :
• the crosscompilation for scala 2.10.6

[mengxr]

Could you also bump Spark version to 2.3.1?

[nekonyuu]

I'm removing the 2.10 compatibility also in Travis, as there's no longer any artifact with 2.10 support unless built by yourself.

Does this looks good to you ?

[mengxr]

LGTM and merged. Thanks!