Added 'tlmgr install xkeyval' to travis.yml
Added 'tlmgr install xkeyval' to travis.yml

Attempted workaround for https://github.com/travis-ci/travis-ci/issues/7863
Rdatatable/data.table,Rdatatable/data.table,Rdatatable/data.table,vlulla/data.table,vlulla/data.table,jangorecki/data.table,Rdatatable/data.table,vlulla/data.table,vlulla/data.table,jangorecki/data.table,jangorecki/data.table,jangorecki/data.table