added FreeBSD to list of supported platforms
added FreeBSD to list of supported platforms

gastrodia/leveldown,phillipj/leveldown,ralphtheninja/leveldown,Level/rocksdb,ralphtheninja/leveldown,MathieuCassagne/leveldown,snowyu/node-nosql-leveldb,MathieuCassagne/leveldown,phillipj/leveldown,jhead/leveldown,Level/leveldown-mobile,No9/leveldown,gastrodia/leveldown,mafintosh/leveldown-prebuilt,MathieuCassagne/leveldown,jmanero/flat-rocks,Level/leveldown,Level/leveldown-mobile,timkuijsten/leveldown,snowyu/node-nosql-leveldb,No9/leveldown,chjj/rocksdown,phillipj/leveldown,ralphtheninja/leveldown,juliangruber/a-native-module-without-prebuild,No9/leveldown,juliangruber/a-native-module-without-prebuild,jhead/leveldown,juliangruber/a-native-module-without-prebuild,Level/leveldown-mobile,No9/leveldown,juliangruber/a-native-module-without-prebuild,ralphtheninja/leveldown,jmanero/flat-rocks,Level/rocksdb,timkuijsten/leveldown,jhead/leveldown,mafintosh/leveldown-prebuilt,juliangruber/a-native-module,gastrodia/leveldown,jmanero/flat-rocks,phillipj/leveldown,gastrodia/leveldown,snowyu/node-nosql-leveldb,chjj/rocksdown,MathieuCassagne/leveldown,ralphtheninja/leveldown,Level/leveldown,snowyu/node-nosql-leveldb,MathieuCassagne/leveldown,timkuijsten/leveldown,jhead/leveldown,timkuijsten/leveldown,phillipj/leveldown,juliangruber/a-native-module-without-prebuild,gastrodia/leveldown,mafintosh/leveldown-prebuilt,jhead/leveldown,snowyu/node-nosql-leveldb,chjj/rocksdown,No9/leveldown,mafintosh/leveldown-prebuilt,Level/leveldown-mobile,juliangruber/a-native-module,juliangruber/a-native-module,jmanero/flat-rocks,juliangruber/a-native-module,jmanero/flat-rocks,timkuijsten/leveldown,mafintosh/leveldown-prebuilt,Level/leveldown-mobile,Level/leveldown,Level/rocksdb,juliangruber/a-native-module,chjj/rocksdown