[PATCH v9 0/5] cat-file: teach cat-file a '--allow-unkown-type' option

The last iteration of the patch can be seen : http://thread.gmane.org/gmane.comp.version-control.git/267213

Changes since last version:

sha1_file:
* eliminate "struct strbuf typename = STRBUF_INIT" in 
"parse_sha1_header_extended()"
* make "unpack_sha1_header_to_strbuf()" work automagically. Now it 
unpacks first 32 bytes and checks if the header is unpacked before 
moving to a strbuf.
* remove unnecessary if condition for "strbuf_release()" .

cat-file:
* change the option name from "--literally" to "--allow-unkown-type".
* make the options mutually exclusive.
* clean up '-s' option.

t1006:
* use echo_without_newline() and added quotes.