Fixed JSON generation and parsing in Ruby driver.
Use %zd for ssize_t

Review 1608 by @danielmewes
Removed obsolete package.sh

Review 1590 by @larkost
merge of #2476 test_report.py requires jinja2

replaces the use of jinja2 with the mustache library, removing the dependency on jinja2
Merge branch 'michel_2497_hasnext' into v1.13.x
Merge branch 'michel_2517_hasnext_dataexplorer' into v1.13.x
Fix copy/paste bug
Uncommented unnecessarily-commented-out code.
Merge branch 'v1.13.x' of github.com:rethinkdb/rethinkdb into v1.13.x
Replaced some enums by enum class for type safety (plus fixed a case of undefined behavior).
Removed additional space
Merge branch 'v1.13.x' into next