Fix/support base reg

[PengBoUESTC]

if we add base config in mpa mode, the createRewire will not create a correct regex for url path, because connect-history-api-fallback use pathname to math the middleware regex, which value is base + xx.html

eg:

base: /testbase/

createRewire regex: for other.html is /^\/other.html*/

connect-history-api-fallback pathname for match is /testbase/other.html

[PengBoUESTC]

for #162

[PengBoUESTC]

@anncwb need review