Accept share input size in bytes, KB, MB and GB

add dropdown to accept the different size scales
implement the logic which converts user entered share size into bytes
Remove Bytes from share input size dropdown.
Add TB in dropdown and change size scales to KB,MB,GB,TB.
Merge pull request #43 from Mchakravartula/issue#19_share_input_size

Accept share input size in bytes, KB, MB and GB