ant-1.9.7 not distributed on apache.org anymore -> ant-1.9.9 (#223)
ant-1.9.7 not distributed on apache.org anymore -> ant-1.9.9 (#223)

* ant-1.9.7 not distributed on apache.org anymore -> ant-1.9.9

* also fixed the caching of the .opam dir on appveyor

touist/touist,touist/touist,touist/touist,touist/touist,FredMaris/touist,FredMaris/touist,olzd/touist,olzd/touist,FredMaris/touist,olzd/touist