XL/fs: Change minioMetaBucket different than '.minio' config dir. (#2190)
XL/fs: Change minioMetaBucket different than '.minio' config dir. (#2190)

This fixes corruption of config directory seen when minio server
exports 'home' directory.

```
minio server ~
```
aead/minio,harshavardhana/minio,luomeiqin/minio,harshavardhana/minio,brendanashworth/minio,jimjag/minio,NitishT/minio,hackintoshrao/minio,aead/minio,jimjag/minio,krishnasrinivas/minio,dvstate/minio,koolhead17/minio,fwessels/minio,harshavardhana/minio,dvstate/minio,brendanashworth/minio,harshavardhana/minio,fwessels/minio,dutchcoders/minio,fwessels/minio,alexellis/minio,abperiasamy/minio,dvstate/minio,aead/minio,jimjag/minio,hackintoshrao/minio,mf-00/newgo,koolhead17/minio,vadmeste/minio,abperiasamy/minio,donatello/minio,aead/minio,minio/minio,krishnasrinivas/minio-daily,dutchcoders/minio,brendanashworth/minio,NitishT/minio,krishnasrinivas/minio-daily,minio/minio,harshavardhana/minio,aead/minio,luomeiqin/minio,krishnasrinivas/minio,alexellis/minio,rushenn/minio,donatello/minio,harshavardhana/minio,NitishT/minio,krishnasrinivas/minio,balamurugana/minio,rushenn/minio,mf-00/newgo,harshavardhana/minio,dutchcoders/minio,hackintoshrao/minio,luomeiqin/minio,jimjag/minio,abperiasamy/minio,krisis/minio,aead/minio,NitishT/minio,luomeiqin/minio,krishnasrinivas/minio,abperiasamy/minio,brendanashworth/minio,balamurugana/minio,krisis/minio,rushenn/minio,rushenn/minio,aead/minio,aead/minio,vadmeste/minio,harshavardhana/minio,hackintoshrao/minio,dvstate/minio,fwessels/minio,dutchcoders/minio