Remove .hgignore, now that we have .gitignore.
Remove .hgignore, now that we have .gitignore.

Refs #354.

BenJenkinson/nodatime,nodatime/nodatime,malcolmr/nodatime,zaccharles/nodatime,BenJenkinson/nodatime,jskeet/nodatime,zaccharles/nodatime,zaccharles/nodatime,malcolmr/nodatime,zaccharles/nodatime,zaccharles/nodatime,malcolmr/nodatime,nodatime/nodatime,zaccharles/nodatime,malcolmr/nodatime,jskeet/nodatime