RemoteFileInputStream#skip returns wrong value

[lexx911]

net.schmizz.sshj.sftp.RemoteFile.RemoteFileInputStream.skip(long n) returns the new file pointer position but InputStream.skip() should return the actual number of bytes skipped instead.

Some stream implementations like Apache Compress GzipInputStream check the return value and throw an IOException if used on an RemoteFileInputStream.

[dkocher]

Attempted fix in #210.

[hierynomus]

#210 is merged, so closing this issue.