Add sudo to pip install command for Linux

[farazs]

fixes #579

[zxiiro]

I don't think I agree that we should add sudo. If you need sudo you should know that you needed sudo.

sudo pip install will install system wide but running pip install as a regular user can also be used to install just for the local user account too which is also a perfectly valid invocation of the program.

[farazs]

Hmm.. so does doing pip install on the freeseer requirements work for some systems but not others?

[zxiiro]

See the PIP user documentation: http://pip.readthedocs.org/en/latest/user_guide.html#user-installs

[dideler]

Agreed that adding "sudo" to the docs is not the right solution. If anything, we can mention that you might need superuser privileges.

Hmm.. so does doing pip install on the freeseer requirements work for some systems but not others?

It depends on how you have your environment set up. You could be using a virtual Python environment, for example, where packages are installed locally instead of globally, therefore not needing sudo.

[dideler]

If anything, we can mention that you might need superuser privileges.

Just noticed we already do mention this. It's in the paragraph above the command.