Handle server URL comparison correctly

[karol-maciaszek]

Chore summary
IHttpOperation merger does not handle all the cases for comparison of server URLs.

Tasks

• host should be compared as case-insensitive
• path should be compared as case-sensitive
• variable names should be compared as case-sensitive (@philsturgeon is that correct assumption?)
• the case, when a variable is a part of hostname, should be handled correctly: host can be compared case-insensitive while variable name should be compared case-sensitively

Additional context
This task is a followup for a discussion here: #83 (comment)

[philsturgeon]

I don't have enough context to know if variable names should be case sensitive or not, I don't think it matters too much either way? Some people will expect it to work one way and others another.