Residual BW may ended up being higher than 100%

[italovalcy]

While running tests for PRs #284 and #283 I found this potential issue when you create L2VPNs with BW requirements and then remove those EVCs, the final value of residual BW may ended up being higher than 100% (!):

urn:sdx:link:ampath.net:Ampath2/3_Ampath3/3 100.001
urn:sdx:link:ampath.net:Ampath1/1_Ampath2/1 100.001
urn:sdx:link:ampath.net:Ampath1/2_Ampath3/2 100.001
urn:sdx:link:interdomain:ampath.net:Ampath2:40:sax.net:Sax02:40 100.001
urn:sdx:link:interdomain:ampath.net:Ampath1:40:sax.net:Sax01:40 100.001
urn:sdx:link:sax.net:Sax01/1_Sax02/1 100.001
urn:sdx:link:tenet.ac.za:Tenet01/1_Tenet02/1 100.001
urn:sdx:link:tenet.ac.za:Tenet01/2_Tenet03/2 100.001
urn:sdx:link:interdomain:sax.net:Sax02:41:tenet.ac.za:Tenet02:41 100.001
urn:sdx:link:interdomain:sax.net:Sax01:41:tenet.ac.za:Tenet01:41 100.001

This is happening because the update link property is not defining a ceiling validation, as it already does for floor validation.