debian/copyright: more fixes

debian/copyright: more fixes

From the License field specification in the Policy: "If there are no
remaining lines, then all of the short names or short names followed by
license exceptions making up the first line must be described in
stand-alone License paragraphs. Otherwise, this field should either
include the full text of the license(s) or include a pointer to the
license file under /usr/share/common-licenses..."

As discussed on IRC, icedove (thunderbird) for example uses a similar
debian/copyright file:
http://sources.debian.net/src/icedove/1:45.2.0-4/debian/copyright/?hl=3742#L3742

This patch solves a lintian warning about missing Licenses paragraphs.

Change-Id: I605e141983e3ac8a4193d196bf6967b6846cc711
Gbp-Dch: Ignore
Signed-off-by: Santiago <santiagorr@riseup.net>