Follow-up fix. Update 0.5.0's dependecy to pyexcel-io

Update 0.5.0 with pyexcel-io v0.5.0 as dependency.

Use pyexcel-io 0.5.0. Performance boost for python2

When you deal with files in memory, you will get performance boost because it uses cStringIO instead of StringIO

Maintenance release

fix #18

Maintenance release

removed useless code

Updated plugin interface and close file handle

#14

Lazy loading

support pyexcel-io v0.3.0

Maintenance release

fix #12

support pagination

see change log for more details

support hidden sheets

deliver #8

adapt pyexcel-io 0.2.0

see change log