Repos should be added to pom

[yoavst]

I have a library that uses a dependency from custom repo:

val repos = repos("https://dl.bintray.com/kittinunf/maven/")

However, the pom file generated from kobaltw uploadJcenter doesn't have this repo declared. Therefore, using the library from other's project doesn't work.

References: https://maven.apache.org/guides/mini/guide-multiple-repositories.html