sweep most unwraps from ethcore crate, dapps crate (#2762)

* sweep most unwraps from ethcore crate

* purge unwrap from dapps server

* whitespace

[ci:none]

dapps/js-glue/src/lib.rs.in

@@ -27,6 +27,7 @@ use std::default::Default;
 pub struct File {
 	pub path: &'static str,
 	pub content: &'static [u8],
+	// TODO: use strongly-typed MIME.
 	pub content_type: &'static str,
 }