blacklist: relax phone normalization

The current E164 is too strict for some valid phone numbers and for regexp numbers. Just
relax that validation a bit while preserve some extra checks for invalid numbers.

JIRA: CYAN-5324
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>

Change-Id: I4783d8c31e28dc50c3dcc69982c81ecd9a0b3d36