Invert case check

Instead of checking for "not A-Z", check for a-z. 
Prevents false positives e.g. if line begins with a number.
Add space before the "(yes or no)" part when asking

Replaces e.g.:

First line doesn't start with a capital letter.  Fix?(yes or no)

with

First line doesn't start with a capital letter.  Fix? (yes or no)
Merge pull request #4 from markus1189/patch-1

Invert case check logic, insert space before "yes or no"