Stratum path doesnt exist on clean Archlinux install, p2pool wont start
## OS & Version:
Archlinux 6.12.4-arch1-1

## Bug
When installing gupax via AUR, trying to start the p2pool will lead to:

[INFO] [11.643] [src/disk.rs:239] ] | Local API Path: "/usr/bin/local/stratum" | Network API Path: "/usr/bin/network/stats" | Pool API Path: "/usr/bin/pool/stats"
[INFO] [11.643] [src/disk.rs:241] --------------------------------------------
[WARN] [11.648] [src/helper.rs:749] P2Pool | Attempting to remove stale API file ... FAIL ... No such file or directory (os error 2)
[INFO] [11.648] [src/helper.rs:773] P2Pool | Entering watchdog mode... woof!


[WARN] [11.649] [src/helper.rs:421] P2Pool API | [/usr/bin/local/stratum] read error: No such file or directory (os error 2)
[WARN] [12.549] [src/helper.rs:421] P2Pool API | [/usr/bin/local/stratum] read error: No such file or directory (os error 2)


## Steps
Steps to reproduce the behavior:
1. Install Gupax via AUR
2. Try to start p2pool


- Windows: `C:\Users\YOUR_USER_NAME\AppData\Roaming\Gupax\crash.txt`
- macOS: `/Users/YOUR_USER_NAME/Library/Application Support/Gupax/crash.txt`
- Linux: `/home/YOUR_USER_NAME/.local/share/gupax/crash.txt`

If you do, please upload or copy-paste `crash.txt` here:
```
Gupax itself does not crash, only p2pool will not start
```
