gnucash master: Put the version back to 3.900.

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/2c637a97 (commit)
	from  https://github.com/Gnucash/gnucash/commit/94bb28d9 (commit)



commit 2c637a9714625344516c630266ed175e4dfff526
Author: John Ralls <jralls at ceridwen.us>
Date:   Sun Apr 28 10:53:17 2019 -0700

    Put the version back to 3.900.



Summary of changes:
 CMakeLists.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)