Flex basis for IE

[kasrakoushan]

Hi! Currently the style prefixer uses msPreferredSize for flexBasis, but IE does not accept this property. Instead it should be msFlexPreferredSize. See the property in the IE inspector below:

Thank you!

[robinweser]

Feel free to send a PR to fix it :) The place to look for it is in plugins/flexboxIE in both /static and /dynamic

[kasrakoushan]

Thank you! I've made a PR here: #135 😃