Fix login issue on Travis-CI FreeBSD build

[nurupo]

This change is 

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[codecov]

Codecov Report

Merging #1145 into master will decrease coverage by 0.4%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #1145     +/-   ##
========================================
- Coverage    82.9%   82.4%   -0.5%     
========================================
  Files          82      82             
  Lines       14473   14473             
========================================
- Hits        12002   11938     -64     
- Misses       2471    2535     +64

Impacted Files	Coverage Δ
auto_tests/network_test.c	90.3% <0%> (-9.7%)	⬇️
toxav/msi.c	63.6% <0%> (-3.1%)	⬇️
toxcore/TCP_client.c	64.3% <0%> (-2.8%)	⬇️
toxcore/TCP_server.c	75% <0%> (-2.8%)	⬇️
toxav/toxav.c	67.2% <0%> (-1.7%)	⬇️
toxcore/group.c	71.7% <0%> (-1.5%)	⬇️
toxcore/LAN_discovery.c	83.9% <0%> (-1%)	⬇️
toxcore/net_crypto.c	92.8% <0%> (-0.8%)	⬇️
toxcore/onion_client.c	94.4% <0%> (-0.7%)	⬇️
toxcore/Messenger.c	85.8% <0%> (-0.2%)	⬇️
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9764285...1a6e8b9. Read the comment docs.

[nurupo]

We change shells from whatever FreeBSD uses to bash, but we didn't change what shell prompt we expect (apparently bash and that other shell have different prompt), so that's why the build was getting stuck on wait_for "root@.*:~" before. Changing that to wait_for "root@.* ~" (the : is removed) fixes it.

[nurupo]

Feel free to merge.