Use LocalLeader for default mapping

[rlue]

Great plugin!

I'd like to suggest that the 'default mapping' for vial-http be changed to use <LocalLeader> rather than <Leader>, or at least for the mapping to be hidden behind a conditional check like if !g:vial_http_suppress_default_mapping.

<LocalLeader> is provided exactly for cases like this, to reduce the chances of collision with users' existing settings:

from :h maplocalleader

<LocalLeader> is just like <Leader>, except that it uses "maplocalleader"
instead of "mapleader". <LocalLeader> is to be used for mappings which are
local to a buffer.

In a global plugin <Leader> should be used and in a filetype plugin
<LocalLeader>.