Scala maps support

[wajda]

Currently velocypack-module-scala only supports immutable Map up to the size of 4.
Basically only the types EmptyMap, Map1, Map2, Map3 and Map4 are serialized correctly.
Other maps (e.g. HashMap, TrieMap, TreeMap, ListMap etc) aren't supported.

[wajda]

I'll send a PR for this one and #9 later today.
I think I'll do both things in one PR as the fixes aren't big to split them, and they have some stuff in common.

[rashtao]

fixed in #11

[wajda]

Hi @rashtao
Has 1.2.0 been deployed to Maven Central?
It doesn't seem to be found there - https://repo1.maven.org/maven2/com/arangodb/velocypack-module-scala_2.12/1.2.0/velocypack-module-scala_2.12-1.2.0.pom

[rashtao]

Sorry @wajda , the deployment failed, redeploying now...