validmeasures/odkr: odkr v0.2.0

This is the second CRAN release of odkr. In this version, I have implemented changes to respond to package issues from CRAN check results.

• In the get_briefcase() function, I changed the download url for ODK Briefcase to the permanent download url provided by the developers at https://github.com/opendatakit/briefcase. This now resolves the issue of apparent download of corrupt jar file.

• All briefcase-releated functions now include a check on runtime of Java availability and Java version checking for a minimum Java version of Java 8. I followed the testing script specified by CRAN in the Writing R Extensions manual.