vsh: Added tests

vsh: Added tests

For now, there are 9 test cases
- testVshTableNew: Creating table with empty header
- testVshTableHeader: Printing table with/without header
- testVshTableRowAppend: Appending row with various number of cells.
  Only row with same number of cells as in header is accepted.
- testUnicode: Printing table with unicode characters.
  Checking correct alignment.
- testUnicodeArabic: test opposite (right to left) writing
- testUnicodeZeroWidthChar
- testUnicodeCombiningChar
- testUnicodeNonPrintableChar,
- testNTables: Create and print varios types of tables - one column,
  one row table, table without content, standart table...

Signed-off-by: Simon Kobyda <skobyda@redhat.com>