Support numeric types in MessagePackParser.getText()

[komamitsu]

Fixes #526

[komamitsu]

@xerial CI failed with this sbt failure. Any insights?

Run ./sbt test
Downloading sbt launcher for 1.2.8:
  From  http://repo.scala-sbt.org/scalasbt/maven-releases/org/scala-sbt/sbt-launch/1.2.8/sbt-launch.jar
    To  /home/runner/.sbt/launchers/1.2.8/sbt-launch.jar
Download failed. Obtain the jar manually and place it at /home/runner/.sbt/launchers/1.2.8/sbt-launch.jar
##[error]Process completed with exit code 1.

[xerial]

@komamitsu We need to update sbt-extra script because Maven has recently stopped supporting http:// repository.

[xerial]

We need to run this command to update sbt script:

curl -Ls https://git.io/sbt > ./sbt

[komamitsu]

@xerial Thanks!