Honor zerombr regardless of clearpart setting.

Fedora
Resolves: rhbz#1143755
RHEL
Resolves: rhbz#1117946
Honor size specified for explicit extended partition requests.

Resolves: rhbz#1077250
Remove obsolete conversion of size to float.

Resolves: rhbz#1140642
Try to align end sector up when aligning new partitions.

Resolves: rhbz#1090477
Align free regions used for partition growing calculations.

Using unaligned free regions only introduces unusable sectors when
calculating growth amounts for aligned partitions.

Resolves: rhbz#1083687
Only pad for md metadata if pvs use multiple disks.