Make `ambush` username matching non-greedy
Make `ambush` username matching non-greedy

Previously messages such as this one would not work:

  ambush Benjie: Hey did you see this link: http://google.com/

because the script would think the username was:
`Benjie: Hey did you see this link`
rather than `Benjie` as expected.

This single-character change matches the first `: ` rather than the
last, thereby solving this problem.

(Only breakage would be for users who have `: ` in their username,
which seems more of an edge case than having `: ` in the message
body.)
justinwoo/hubot-scripts,jacobtomlinson/hubot-scripts,dyg2104/hubot-scripts,yigitbey/hubot-scripts,ericjsilva/hubot-scripts,josephcarmello/hubot-scripts,zecahnin/hubot-scripts,opentable/hubot-scripts,jankowiakmaria/hubot-scripts,1stdibs/hubot-scripts,alexhouse/hubot-scripts,dbkaplun/hubot-scripts,jhubert/hubot-scripts,Ev1l/hubot-scripts,ryantomlinson/hubot-scripts,sklise/hubot-scripts,dhfromkorea/hubot-scripts,modulexcite/hubot-scripts,MaxMEllon/hubot-scripts,n0mer/hubot-scripts,Tyriont/hubot-scripts,GrimDerp/hubot-scripts,markstory/hubot-scripts,fromonesrc/hubot-scripts,github/hubot-scripts,magicstone1412/hubot-scripts,terryjbates/hubot-scripts,jan0sch/hubot-scripts,amhorton/hubot-scripts,cycomachead/hubot-scripts,chauffer/hubot-scripts,contolini/hubot-scripts,arcaartem/hubot-scripts,ambikads/hubot-scripts,iilab/hubot-scripts,wsoula/hubot-scripts,phillipalexander/hubot-scripts,azimman/hubot-scripts,1000hz/hubot-scripts,davidsulpy/hubot-scripts,marksie531/hubot-scripts