style: reorder jdk versions in .travis.yml
style: reorder jdk versions in .travis.yml

Reorder the openjdk versions in .travis.yml so that openjdk6 comes before openjdk7.

phillipross/pgjdbc,jamesthomp/pgjdbc,zemian/pgjdbc,marschall/pgjdbc,davecramer/pgjdbc,underyx/pgjdbc,zapov/pgjdbc,jkutner/pgjdbc,whitingjr/pgjdbc,sehrope/pgjdbc,amozhenin/pgjdbc,AlexElin/pgjdbc,pgjdbc/pgjdbc,bocap/pgjdbc,golovnin/pgjdbc,sehrope/pgjdbc,Gordiychuk/pgjdbc,Gordiychuk/pgjdbc,amozhenin/pgjdbc,pgjdbc/pgjdbc,bocap/pgjdbc,jorsol/pgjdbc,whitingjr/pgjdbc,davecramer/pgjdbc,rjmac/pgjdbc,schlosna/pgjdbc,pgjdbc/pgjdbc,lonnyj/pgjdbc,bocap/pgjdbc,AlexElin/pgjdbc,golovnin/pgjdbc,jkutner/pgjdbc,zemian/pgjdbc,AlexElin/pgjdbc,zapov/pgjdbc,jamesthomp/pgjdbc,lordnelson/pgjdbc,zemian/pgjdbc,whitingjr/pgjdbc,sehrope/pgjdbc,jamesthomp/pgjdbc,phillipross/pgjdbc,marschall/pgjdbc,marschall/pgjdbc,panchenko/pgjdbc,rjmac/pgjdbc,pgjdbc/pgjdbc,panchenko/pgjdbc,rjmac/pgjdbc,Gordiychuk/pgjdbc,davecramer/pgjdbc,alexismeneses/pgjdbc,lordnelson/pgjdbc,panchenko/pgjdbc,golovnin/pgjdbc,amozhenin/pgjdbc,underyx/pgjdbc,jorsol/pgjdbc,lordnelson/pgjdbc,jorsol/pgjdbc,davecramer/pgjdbc,sehrope/pgjdbc,zapov/pgjdbc,jorsol/pgjdbc,phillipross/pgjdbc,schlosna/pgjdbc,marschall/pgjdbc,jkutner/pgjdbc,lonnyj/pgjdbc,underyx/pgjdbc,alexismeneses/pgjdbc