Fix #140: Added RecordReader for reading records from a reader.

The RecordReader class reads data from a Reader and splits it at a
user-defined character.
Added RecordReader to flux-commands.
Changed default separator to the global separator (0x001d).
Added support for setting separator from string.

Flux cannot set option values of type char. This commit adds a
setSeparator method which uses the first character of a string as
separator. If the string is empty, then then separator is reset to its
default value.
Merge pull request #142 from cboehme/issue-140-record-reader

Fix #140: Added RecordReader for reading records from a reader.