Fix expliciti basic_auth for http
Fix tomcat_mgr_login auth
trust any manualy set basic auth header

for now we will assume the module author knows what they are doing.
Missed nil check
Merge branch 'bug/basic_auth' of https://github.com/dmaloney-r7/metasploit-framework into dmaloney-r7-bug/basic_auth
Merge branch 'dmaloney-r7-bug/basic_auth', see also #1477 and #1444, #1477, #1472