[#89 #150] [Fix] Boxed Booleans incorrectly freezing to primitive true (@RolT)

Before this commit:
  (freeze true)                  => froze as primitive `true`
  (freeze false)                 => froze as primitive `false`
  (freeze (Boolean. <anything>)) => froze as primitive `true`

After this commit:
  Boxed Booleans are first unboxed to correct primitive value before freezing

This was a long-standing bug, though thankfully unlikely to have affected most
users since boxed Booleans are rarely used in Clojure. Cases with Java interop
are the most likely to have been affected.

A big thanks to Roland Thiolliere (@RolT) for this fix!

README.md

@@ -61,6 +61,7 @@ nippy/stress-data
  :nil       nil
  :true      true
  :false     false
+ :False     (Boolean. false)
  :char      \ಬ
  :str-short "ಬಾ ಇಲ್ಲಿ ಸಂಭವಿಸ"
  :str-long  (apply str (range 1000))

src/taoensso/nippy.clj

@@ -1151,7 +1151,7 @@
   (.writeLong out (.getMostSignificantBits  x))
   (.writeLong out (.getLeastSignificantBits x)))
 
-(freezer Boolean              (if x (write-id out id-true) (write-id out id-false)))
+(freezer Boolean              (if (boolean x) (write-id out id-true) (write-id out id-false)))
 (freezer (Class/forName "[B")                  (write-bytes   out x))
 (freezer (Class/forName "[Ljava.lang.Object;") (write-objects out x))
 (freezer String               (write-str   out x))
@@ -2020,6 +2020,7 @@
    :nil       nil
    :true      true
    :false     false
+   :False     (Boolean. false)
    :char      \ಬ
    :str-short "ಬಾ ಇಲ್ಲಿ ಸಂಭವಿಸ"
    :str-long  (apply str (range 1000))