parse_version improve/fix tests

For samples like "$Something::VERSION == 1.0" we're testing
that parse_version returns "undef" (string).

However, I believe, we should tests that it never tries to eval() it

Before this fix samples like "$Something::VERSION == 1.0"
evaled, and result was undef. But code like:

my $x = $Something::VERSION == 1.0 ?
   "abc" : "def"

will fail if we try to eval first line.
parse_version - fix regexp and tests

fix regexp and tests for samples like $Something::VERSION == 1.0
addresses RT#9452 regression Jul Y2013
Merge pull request #62 from vsespb/master

Fix parse_version tests and improve regexp