After seeing your problem I found out that you have defined your dependency as:
"org.apache.spark" %% "spark-core" % "1.0.2"
As I can see, you have used %% instructs sbt to substitute current scala version to artifact name. As far as I am concerned, spark was build for the whole family of 2.10 scala, without specific jars for 2.10.1, 2.10.2 ...
So to resolve your problem you just have to redefine it as:
"org.apache.spark" % "spark-core_2.10" % "1.0.2"