Fix internal pattern match for JIRA issues as per https://confluence.atlassian.com/display/JIRA/Changing+the+Project+Key+Format
Removed lowercase matching as it is not allowed in JIRA issues
Modified the test with no jira issues in order to test abc-123 is invalid
Modified the test with a jira issue in order to also test the issue ABC_D-123 is valid
Merge pull request #2 from agusmba/fix_internal_regexp

Fix internal pattern match for JIRA issues