Always specify what base type we want returned from parseInt()

Bug 1394330

In most places in mahara we specify that we want base 10 number
returned (or base 16 in case of a hexidecimal css colour)

But there are a few places where we don't specify the radix at all

It's best practice to always include the radix because for older
browsers it interprets leading 0 as octal by default.

Also makes it clearer to developers what type of number is expected to
be retrieved from the string.

Change-Id: Iaecc85cbed875f85b313188c4e96cc1b77c77b31
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>