auth: LsatAuthenticator -> L402Authenticator
sed -i 's/LsatAuthenticator/L402Authenticator/g' aperture.go auth/authenticator.go auth/authenticator_test.go
rename package lsat to l402
git mv lsat/ l402
sed 's@aperture/lsat@aperture/l402@g' -i `git grep -l aperture/lsat`
sed -i 's@package lsat@package l402@' `git grep -l 'package lsat'`
sed -i 's@lsat\.@l402.@g' -i `git grep -l 'lsat\.'`
sed 's@l402.Id@lsat.Id@' -i mint/mint_test.go
replace lsat with l402 in the code
sed 's@lsat@l402@' -i mint/mint_test.go
sed 's@Lsat@L402@' -i l402/client_interceptor.go
sed 's@lsatstore@l402store@' -i l402/store_test.go
replace LSAT to L402 in comments
sed '/\/\//s@LSAT@L402@g' -i `git grep -l '//.*LSAT'`
replace LSAT -> L402 in the code, skip when a string starts with it
sed 's@\([^"/]\)LSAT@\1L402@g' -i `git grep -l LSAT`
The new package contains a new interface (`Challenger`) that any
new challenger must implement.
Because aperture uses the new interface instead of using directly the
`LndChallenger` struct I added the `Stop()` method to the
`mint.Challenger`. Instead of also adding the `Start()` method the constructor
returns a Challenger already "started".
