Description of problem:
There is a typo in error message when input unknown output format for virt-convert,
when run command "virt-convert -i virt-image -o vmx123 image.xml", the error message would display:
"virt-convert: error: Unknown output format "vmx123")", the last bracket should be removed.

There are also two other two error messages have the same issue.
virt-convert: error: No output handler for format "ovf")
virt-convert: error: Unknown input format "asdf")


Version-Release number of selected component (if applicable):
python-virtinst-0.600.0-8.el6.noarch

How reproducible:
100%

Steps to Reproduce:
Run a virt-convert command with unknown output format
# virt-convert -i virt-image -o vmx123 image.xml
check the error message

Actual results:
virt-convert: error: Unknown output format "vmx123")

Expect result:
virt-convert: error: Unknown output format "vmx123"