fix rollback panic bug (etcd-io#153)

remove excessive []byte(s) conversion (etcd-io#143)

`copy` permits using to mix `[]byte` and `string` arguments without
explicit conversion. I removed explicit conversion to make the code simpler.

Signed-off-by: Iskander Sharipov <[email protected]>

Merge pull request etcd-io#65 from zrss/fix-page-cnt

tx: fix the number of pages is incorrectly counted

Merge pull request etcd-io#67 from heyitsanthony/fix-freelist-corruption

Fix freelist corruption on tx.WriteTo

Merge pull request etcd-io#66 from jpbetz/freelist-check

Panic if page provided to freelist.read is incorrect page type.

Merge pull request etcd-io#64 from kwf2030/master

fix funlock error when call db.Close on windows

Merge pull request etcd-io#56 from virtualsue/master

Trivial. Removed 'moribund' from README.md

Merge pull request etcd-io#28 from gyuho/goreport

goreport + minor fixes