add an experimental base class for multiple inputs scanners
s/NULL_DICT/DICT_MZERO/g (monoid)
add scanner for uname's output as a simple parser example, and its test cases
simplify sos_analyzer.scanner.base.SimglePatternScanner
bug fix in a regex for uname's contents
enable sos_analyzer.scanner.uname.Scanner
fix a bug that test code loading wrong module
fix a bug in test cases causing the out of range of index error
add scanner for /etc/hosts
add scanner for /var/log/messages
enable some more newer scanners
add scanner for 'df' outputs
enable some 'df' scanner
add df example outputs