Fix improper formatting of <text><span> in LIFT files

This fixes http://jira.palaso.org/issues/browse/WS-34794.
Also ensure that the LIFT file is ordered consistently and that only
NFC Unicode is written out.  Both of these changes help with comparing
files without meaningless differences.
Merge pull request #58 from sillsdev/Fix-WS-34794

Fix improper formatting of <text><span> in LIFT files