Make `pip.installed` actually upgrade Homu

[aneeshusa]

It seems like the pip.installed state currently is failing to update Homu to newer versions when the git revision changes, requiring manual upgrades.

Temporary manual upgrade procedure:

• Stop Homu with service homu stop
• Back up the Homu database (currently located at /home/servo/homu/main.db)
• Blow away the Homu dir (/home/servo/homu)
• Run the Salt highstate to install the upgraded Homu
• Replace the Homu database

[jdm]

This also affects the version of https://github.com/servo/intermittent-tracker/ that's in use; it seems like the only steps necessary there would be:

• Blow away the Homu dir (/home/servo/intermittent-tracker)
• Run the Salt highstate to install the upgraded intermittent-tracker

[aneeshusa]

I haven't checked, but I think #623 may have fixed this.

[jdm]

Pip installs fine from git sources when using the --upgrade flag. Adding the equivalent flag in salt makes this work.

[jdm]

#623 definitely should have fixed this.