Project path and lcov path options are failing

[Jan Grodowski]

Reproduce

• run from a directory different than target dir: undercover -p path/to/project
• fails to guess the lcov path, because it starts looking in pwd

Or:

• run from a directory different than target dir: undercover -p path/to/project --lcov path/to/project/lcov.lcov
• fails to parse files, because parser receives relative paths (need to prepend project path or make them absolute)

Sample backtrace:

./undercover/bin/undercover -p undercover -l undercover/coverage/lcov/undercover.lcov -c HEAD~5
/Users/mrgrodo/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/parser-2.5.1.0/lib/parser/base.rb:65:in `read': No such file or directory @ rb_sysopen - lib/undercover.rb (Errno::ENOENT)
	from /Users/mrgrodo/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/parser-2.5.1.0/lib/parser/base.rb:65:in `parse_file'
	from /Users/mrgrodo/dev/undercover/lib/undercover.rb:80:in `block in each_result_arg'
	from /Users/mrgrodo/dev/undercover/lib/undercover.rb:78:in `each'
	from /Users/mrgrodo/dev/undercover/lib/undercover.rb:78:in `each_result_arg'
	from /Users/mrgrodo/dev/undercover/lib/undercover.rb:35:in `build'
	from /Users/mrgrodo/dev/undercover/lib/undercover/cli.rb:28:in `run'
	from ./undercover/bin/undercover:11:in `block in <main>'
	from /Users/mrgrodo/.rbenv/versions/2.4.4/lib/ruby/2.4.0/benchmark.rb:308:in `realtime'
	from ./undercover/bin/undercover:10:in `<main>'